Linear progression and a few other flaws don't hamper this game from being awesome.
I am not sure if I was blinded by the excessive wait, or the sheer joy of playing a new Final Fantasy, but I really loved this game. I have not enjoyed a Final Fantasy this much since the old PSone FFs. I felt it had many of the things that made the older FFs great. Like great story, great characters (well, maybe most great characters, and one....yeah), and awesome battle system. I don't want to go into detail about things such as story because I don't want to spoil anything. But, the battle system is great and is really fast paced, and while simple at first, does grow into a very complex being by the end of the game.
Now, there are a few things that bugged some people which didn't bother me at all. One, for instance, was the lack of towns (ie places were you go and buy crap). Now, if you play, or know anything about his game, the general populace fears, hates, and wants your destruction. So, I believe it is very forgivable from a story perspective, because if the main characters know their faces are plastered everywhere then why the hell go where they know they will find trouble? Another thing I found to be forgivable was its very linear progression. It was very much like FFX in that the maps are a narrow corridor and there is but only one path to go, forward. However, I found this forgivable as well, because the story has so much forward momentum that you want to go and keep playing and keep pushing forward to find out just what the hell is going on. I am sure there are more things, but I can't think of them right now.
Now for the stuff that actually bothered me. The main thing was Vanille. Vanille has a few flaws within her that doesn't make her as strong a character as the others, but the one things that bothered me the most was the voice acting. For some parts, she has an Australian accent, others, she does not. She switches between the two at will and none of the other characters take notice at all. Wouldn't you notice if someone just suddenly dropped their accent for no reason at all? Like that episode of Friends when Ross was teaching with a British accent and suddenly dropped it and the students noticed right away. If other characters had asked about the bizzare change of speech, this would not have been as much a problem. Now, another thing that really could get my gears grinding was that if your character dies in battle, doesn't matter if the other two are medics or not, it is game over. This got on my bad side alot as sometimes every enemy would just start attacking my character without remorse and I could not get a chance in to heal and boom game over.
The last thing that did actually bother me a bit was the really linear progression, now I know I said it was forgivable because of story reasons. I just miss the old FFs with the huge open world map, and having the airship to fly around in. That is why it kind of bothered me, but for this game, I still find it more forgivable than most do.
This game is a must for fans of the series. I think it is a worthy addition to the franchise and easily was worth the long wait.