Ooookaaaay
The game finally unlocked on Friday. And now I am kinda thankful that it did, seeing how it swallowed me whole over the weekend. So here's my Review.
1. The good:
-The Story. Not only is there one, in sharp contrast to the first Borderlands, it is also very well written. Handsome Jack is a great antagonist, starting off as a real dick who keeps calling you to either tell you how awesome he is, or how bad you are at your job. As the story progresses, there are moments where his facade slips and he goes from dickishness to real villainhood, which serve to give him an actual arc.
The player characters from the first Borderlands make a reappearance as NPCs, each of them is given a good intro, and some (all? don't know, haven't played through yet) even have genuinely touching moments.
-The Graphics
The original Borderlands wasn't supposed to be cell-shaded, it was only after a last minute art style change that we got the game we eventually arrived at, and when comparing BL1 and BL2, this becomes rather apparent. BL2's art is gorgeous (At least on a PC with texture details cranked to max), there are awesome sights in every region you get to visit, and the effects work is equally good. The godray effect seen in the latest Unreal3 games (ME3, Batman: Arkham City) is present, here enhanced with some subtle colouring hints.

On the subject of art style, the guns also got a desperately needed upgrade. There's greater graphical variety between the various brands, and most of them actually look and feel unique rather than reskins of the same model with some under-the-hood stat changes.
-The Gameplay
It's like the first Borderlands, only more so. As stated above, the guns now look more varied, and the associated gameplay is more varied too; but not only did the guns get an upgrade, the rest of the inventory did as well. Grenades can now combine several effects, instead of being limited to a deployment mode + effect combo; I am currently running around with 'nades that give all victims a slag effect (weakening their defense for a time) and a health-leech effect, which is nice.
There are two models of cars now, the light runner from the first one, and a Bandit 4-seater. Nothing much to say there, really.
The first Borderlands used a stat tracking mechanism whereby completing certain goals would give you an XP boost, Gearbox wisely reinvented this and turned it into so-called Badass points, which unlock tokens that can be redeemed for some stat boosts (Not very big ones, I hasten to add) that carry over to all characters you play, which is a nice refinement of the Achievement system seen in modern games.
-The Sound
It's good. Sound design is nice, music serves the story. Nothing really outstanding here.
2. The bad
-Difficulty curve
Much like the first game, you level pretty fast in this one too. Unfortunately, this means that sooner or later, you're stuck with your quest log filled with tasks that are of trivial difficulty; I really wished they'd have implemented a level scaling system here so that quests retain the same level of challenge regardless of how high-level you are.
....
I think that's it, really. Maybe I'll have more to add later.