I have to disagree. To me, B1 was a lot better than B2.
B2 was like a console port to the pc. It seemed just too scripted for my taste.
B1 had its badparts, but it was overall a solid game.
I used to prefer BL1, but I have since changed, after going back and trying to play through BL1 again.
First--I'm not sure how BL2 is like "a console port to PC" and BL1 isn't? Mechanically, they are virtually identical. Interface, save spots, questing, leveling and skills, etc (same for both). I guess I'm not sure what you mean by that--and how it can't apply to BL1 equally.
BL1 feels very much dated in comparison--the AI pathing is pretty bad, the run mechanics don't feel as solid and natural as they do in BL2.
BL1 has 2 classes out of 4 that are very good. The other two (Soldier) are weak, or completely useless (Brick/Berzerker). BL2 has, basically, 3 out of the 4 base classes that are very good to, well, OP (Gunzerker), and the 2 bonus pack classes are very fun, and quite unique, and very good at late game.
DLC is almost equal--Knoxx for BL1 is amazing, likewise Tiny Tina's for BL2. BL2 has much, much better story elements (BL1 had no story...at all) and better characters overall (as one example--Torgue Flexington is just amazing--need Torgue's DLC) and Jack is an actual villain, which is something that is completely missing from BL1. The only interesting character in BL1 is General Knoxx, which requires his DLC.
The main campaign in BL2 is much longer and while the broken playthrough system (need to beat the game once to unlock the second playthrough to play the "real game") is still there, you aren't going to overlevel yourself like one does in BL1 about 20% into the game. So, at least something was fixed with that problem...
The only thing that I think is better in BL1 is the gun randomization (Actually more potential guns) and totally random loot drops. Legendaries dropping from certain bosses in BL2 is nice, and if you are into farming one will probably dig that...but the way the guns are balanced in BL2, many of those legendaries are necessary to get through UVHM and DLC (in UVHM). With BL1, there were still plenty of very good blue/purple guns. Yes, there are a few very good blue guns in BL2, but they tend to be limited/mission specific items that you will rarely see in a loot table.
But, I digress--the prices on Steam today are PATHETIC for BL2. Do not buy BL2 on Steam today or any of its content at those prices. It has been much, much cheaper almost a dozen times over the last month or so, even on Steam.