To get to the level and skill your at now is a piece of cake, if you didn't know you can set specific abilities for your GF's to learn, several of which are magic refine abilities, which Quezacotles cad mod ability you can mod your high level GF cards into great items then take those items and mod them into powerful magics, also another great tip (if you are willing to wait) is that when your given the Magic Lamp don't use it right away, instead wait till all your party members reach an average level of 30 then use it, why 30? because you can draw the powerful magics Holy and Flare, so you can pretty much devastate anything from that point on if you junction them to Squall's strength stat and HP stat.

With regards to how worth it that is is entirely up to you, I know I had to restart my game the first time I played it but that was because my brother stupidly saved over my file.