Right, because it seems to be possible to predict closely what people will think of FF13 based on their opinions of FF10 and FF12, I'll start this by saying that I loved both games, though my preference is definitely for 12. Those of you who now think I'm retarded, please stop reading now. Clearly we are of such different preferences that no conversation on this topic is possible.
I more or less agree with Funk's review, in that I think the game starts off achingly, patronisingly slow, but is carried along by an impressively well-realised cast of (varying degrees of) assholes (major points, by the way, to Square for actually letting 'you' - Lightning - punch Snow in the face for being annoying XD) and nice-guys. It does come together neatly about the 25-hour mark, if you can get that far, and after that, there's some genuinely enjoyable, inspiring gameplay. I still get a shiver down my spine looking out across the Archylte Steppe.
There are two problems I've had with the game, though, that haven't seen much mention. Firstly, the rewards for each ordinary encounter feel frustratingly weak through most of the game, both in terms of XP and loot. I've never felt so strapped for cash in the final third of an FF game, never mind how tedious grinding upgrade items can be (I'm just past 70 hours in, deep in the optional content, and I've still not seen a Trapezohedron). It doesn't sound like it should be a substantial issue, but it makes the not-so-random encounters feel like such a chore, particularly since at lower levels, ordinary monsters can take several minutes to kill.
The second problem, for me, is the ending. I have to apologise; I don't know how to do spoiler cover-ups, so I'm going to try to describe my problem without spoilers. The warning signs come when you figure out who the main villain is, because the main villain is pants. You can see what Square were shooting for, but they're wide of the mark in every way; he's a scenery-chewing monster that you couldn't take seriously if he were real and had you at gun-point, and the attempt to give him motivation and sympathy falls completely flat because of it. No-one with supposedly noble motivations EVER cackled that hamishly over the heroes.
Far worse than that, though, is that at a point about 40 hours in (around the end of chapter 11, once everything's out in the open), two bizarre and distressing changes come over the central cast. Firstly, they stop being able to say anything that isn't either a whiny loss of faith or a farcical, cod-inspirational soundbyte barely worthy of a presidential candidate, and every cutscene for the remaining ~10 hours of the game consists of one of them whining and then the rest effectively saying 'Come on, don't give up!' in the most trite ways possible.
The second, more damaging, thing is that their actions stop making any sense at all. There are a couple of points where everything the characters have ever said they're trying to do goes out the window so they can smash stuff. The first of these happens at the start of chapter 12 and is mostly superficial given how the machinations of the bad guy unfold shortly afterwards. The second is actually the set-up for the final boss of the game. I'm sure most people reading this are familiar with what happens with the final boss of FF9 (again, I'm trying to avoid spoilers - sorry for my ineptitude); it's been the consensus of my housemates that this is at least as inexplicable, albeit slightly less random. Given how far the story and characters carry the game, to have them collapse on the final straight is really frustrating.
Having the final part of the levelling system - the bit that makes some of the optional content conceivably doable - only unlock after you beat the final boss is galling, as well, but that's a minor niggle.