Do not turn this into a VI vs. VII debate...^^
For the topic at hand, yes I noticed the similarity between the two, it wasn't hard to imagine since it was mostly the same core team that did both with two omissions (Sakaguchi and Nojima).
To me, X was a streamlined version of the PS1 generation, sucking away that bothersome "exploration" crap the kids didn't talk much about in those days (mostly cause we expect it) and while X offers many mini-games on the way to do to break up the monotony, I never found any of them engaging and most of them felt really out of place "catch... butterflies? While Sin is destroying the land?". Yet, if XIII taught me anything, its that something is better than nothing.
My main issues with X was that in comparison to the the rest of the series and the impact they did for their time, I always felt X was simply mediocre. It really didn't do anything novel or interesting. Its biggest impact was making other designers realize that it was okay to create linear world design as long as you had lots and lots of cutscenes to keep the player entertained and so part of me wants to kinda blame X for the fall of the JRPG in the last generation of gaming cause I always felt X's game format was backtracking when compared to the superior FFIX that expanded exploration and really took some creative steps with overworld map designs and gameplay.
X failed for me cause it didn't wow me, it felt like several of the more generic rpgs I was playing on the PS1 in anticipation for the PS2 era.
Despite this, X is the FF equivalent of Oblivion when compared to XIII which took X's suffocating design and format and streamlined it even further. Fans have joked (well some have others probably meant it) that FF was getting to a point where it was going to be less of a game and more of a movie and that's really what I felt XIII strived for and why I felt it failed as a game cause for me there was little game to speak of and what was there was not satisfactory. I feel XIII has made me appreciate X more but I still have ill feelings toward X cause I felt X could have been great if it wasn't so obsessed with its story, and actually gave the player more elbow room to create their own pace rather than let the narrative create the pace for you.
Both games had linear map design but at least X had a few diversions on the way. Though I give XIII props on making most of the locales more interesting to look at cause personally I never liked the design of several of the "maps" in X and it was places like the Mihen Highroad and Mushroom Rock that made me realize the linear design of the world.
Both games tout a system they feel is highly strategic for the player to interact with. Yet X is crippled cause its system is built around end game content and the main quest is nerfed to all hell so the player doesn't miss the story cause that's all they really care about... right? XIII's feels fun in the beginning but after awhile you just realize you are basically do the equivalent of grinding in XII for a friend where you battle enemies but are forced to stick to another person's Gambit set-up you are not allowed to touch lest he denies you the pizza he promised. So basically by the end you are just switching back and forth from different A.I. scripts and occasionally watching the health to know when to switch to another. The game also rewards you for fighting quickly so even the challenging optional fights feel more like normal encounters when done right. On the one hand, I commend XIII for at least trying to make amend for where X faltered by not making the complex and wonderful nuance elements of the combat system exist purely for the optional content that opens up at the 11th hour of the game and makes the rest of the games combat feel like a chore but I also wish to reprimand XIII for creating the scenario that mostly bitched and moaned about with XII which was that it was more like babysitting an A.I. At least when you took control of the characters in XII you actually had more options of what to do, at least you had the ability to actually control your whole party and if you used the A.I. it actually was based on what you felt was priority.
Its a real shame for both titles cause I had high hopes for both of their combat systems but at least with X, I got the better version of it from Persona 3 who you know, actually made it worth your while to use cause it actually had the balls to be hard and force the player to think strategically instead of making the majority of the games difficulty trying to figure out how to win a battle without losing MP or HP which frankly was never really hard in the first place.
XIII on the other hand borrowed from Xenosaga II's system and I'm just starting to think I really don't care for this gameplay format cause it just seems like no one knows how to use it properly.
Both games, for me at least, had sub-par and downright terrible casts in which both titles had at least one character with good character growth who sadly is also the most obnoxious cast member (Hope and Wakka) the rest feel like variations of people we've seen before and sadly the most interesting characters usually get less screen time than the more bland cast members. Both also featured sets of villains who were mostly forgettable.
Oddly enough, I wish both titles could have taken a lesson from the other in this regard as I felt XIII actually had a few villains that would have worked well for the story if they were used better. Whereas I felt X would have been a better game if they had dropped Seymour and the cliched tale of a corrupted church in favor of focusing more on Sin and would have allowed them to cut out down some of the slower parts of the story. Go figure.
Most of what bugged me about each story was just how predictable the plots were. I was rarely surprised by anything that happened in the stories and what few caught me off guard usually felt entirely out of place for the story imho. In X's defense, I felt its problem was simply not just that the story was predictable but it was poorly paced for me, I know the story, I know how this will most likely end so let's get on with it. Yet, at least its still and interesting story. I just hated how it was told cause it was long winded for my taste.
XIII is not only terribly long winded but constantly settled for the lowest common denominator. At several times, the story could have gone down a more meaningful path and actually force the player to look at the scenario beyond what was going on but instead it dropped such concepts like a stone and moved on. It wouldn't have been so frustrating if the game didn't keep teasing the player with such nonsense.
In reality, XIII has two plots, the first half is built up of the character driven story of watching the party go through the five stages of grief and then theirs the "fantastic and epic" tale of watching your party being taunted by a douche bag villain who wants them to fight and kill him even though that is what they were going to do anyway. The first half is not as well done as I would like and I felt the writers went overboard on the angst but it was smurfing brilliant compared to the second half of the game whose story just openly falters at every turn. This is the main problem with XIII for me, what parts of it are good are not actually good in themselves, they are just good in comparison to the obvious crap that is the rest of the content, its like being asked to study a pile of crap and asked to pick out the best part. Sure you definetly picked the best part but it doesn't really change the fact it is still crap.
X is bad cause it never truly achieved the greatness it could have been, the pieces are all there but it always stops short of it. Its just feels less impressive compared to the what the rest of the series did but more importantly, it feels less impressive compared to other titles in the genre itself. Suikoden III was released around the same time as FFX and it is an infinitely better game that features a more unconventional and interesting cast, a battle system based on utilizing the best party, and a narrative story that tells the tale of a conflict from three (technically five) perspectives and overall makes the player see that you cannot simply take things for face value. X is not a bad game, it just settled for mediocrity.
XIII doesn't have the same issue, its just a badly designed game that takes the most aggravating parts of X (not living up to its potential) and takes it further than the other would dare to go. The difference between both is that I feel we can debate the merits of X (and I'm sure many of you will) but I don't feel the same for XIII. You can state problems with XIII's writing and system and I feel apologists will be hard pressed to come up with any convincing answer as to why it was a good thing. The faults in the writing are far more glaring and obvious. The only way to appreciate XIII is to not look at it as a wonderful narrative with exciting gameplay but rather as just a nice diversion to keep you busy while you wait for something more substantial to come out and wrap your brain around.
For the ADD crowd: X is mediocre but not bad, XIII is just plain bad.