Really LTTP, but I just started this; about 7 hours in.
The first hour or two was pretty horrible - I'd heard the "tubes" comment before and the linearity complaints, so I didn't have high expectations, but yeah, running down corridor after corridor with little to no sense of exploration was pretty bad. The limited camera options don't help - camera feels clunky and constrained, even claustrophobic at times. Which is unfortunate, since the environments are uniformly gorgeous, but I kept thinking, "What was the point of putting all that time and money into designing these beautiful backdrops if they're basically empty and I'm just going to run through them? Might as well have stuck with pre-rendered backgrounds from FFVII and saved the trouble".
Introducing battle mechanics with "press X to auto-battle and win" didn't help either. It really felt like they'd stripped things back even from FFXII. Lack of experience points, getting scores which apparently don't mean anything and star rankings really make you wonder why the hell you're bothering fighting enemies. In fact, I still have no idea what the point is of the scores, and the star rankings apparently influence what items you get? (but apparently, if you do worse you sometimes get better items like smokes?)
I have to say, though, that now that the game's introduced paradigms, character progression, etc., it's gotten a lot more fun. Combat feels much more engaged, even arcade-y - you actually have to be involved, which is sort of a welcome change from FFXII and even from earlier FF's. So high marks on that.
Don't know where I stand on the characters / story yet. I'm not a fan of the storytelling device of "let's throw around a lot of random made-up terms and have you figure out what they mean from context later on". I can't make sense of Vanille's accent - an Australian accent which switches in and out, sometimes unbearable girly / cutesy, sometimes adult-sounding. Hope is whiny and annoying. Lightning is all monotone, all the time. Sazh's voice-actor, however, gets high marks - his character borders on stereotype as comic relief (and are they serious with the afro as chocobo-nest?), but at least he has "character".
So yeah, first take - horrible pacing in first few hours; they could have done a much better job with how and when they chose to introduce battle concepts and plot points. If I'd just played the first hour I would have put it back on the shelf. But at least the combat is actually getting fun.