I would hardly say FFVI has a class system. Sure, each character has a special ability and you can only equip certain items on certain people. Insofar as that is true, there are classes, however the lines are very blurred with Espers. Traditionally, magic is not open to every class. I'd say FFVI has as much as a class system as FFX: it is only a class system as much as you allow it to be. Sure Rikku is a "thief" class as well as Locke, but hey let's give Locke an Esper and Rikku learn a bit of Lulu's Sphere Grid and now they're mages as well! FFVI class system is more of a pseudo-class system in all honesty.
Relic system? Seriously? It is just the same as equipping accessories in most other RPGs, just this time you get two. Though the Gametrailer video review is the first time I heard about the crafting system for the weapons in FFXIII and from their impression it is underwhelming.
As for linearity, FFVI, along with a few others, are pretty linear until you get an airship or something similar. Basically you have the town NPCs more or less drawing you a map where to go next. Sure, you have that nice big open world map to go to, but for the most part at the beginning of the game all other areas are conveniently blocked off, leaving your next destination very obvious. Not so coincidental and ever so convenient, the only place you can go is the place that all the earlier NPCs were talking about and the next plot point! Not to say they don't open up, they do, but it only occurs later in the game. Sure, it seems open but if you look close enough they are just giving you slack on the leash.
That being said, FFVI is still one of my favourite instalments in the series (along with FFT and FFXII).
The reviewers complaining about melodrama make me laugh though. It is like they haven't played most JRPGs or watched anime. Sure, they are not all like that but it is common enough that it shouldn't be surprising. To me, it is like complaining about the fact that most RPGs are about saving the world or some re-iteration thereof.
Give me a good battle system and an engaging plot and/or characters and I am pretty much set.