Just like the first but offering more story, more varied colorful environments, personality, loot, guns and gore and..well you know the deal. I would've given a flat out 10 except the storyline of the Evil insensitive rich guy, drilling for the vault (instead of Oil) is a tired Hollywood meme and just too easy. Fortunately, the Protagonist is pretty darn funny anyway. Whats also great is that the characters from the first game are now no longer playable but featured as essential story elements. You also feel little more connected to the Character than the first. It also is a bit more focused it how it directs you. the game pushes you forward to keep the story flowing - as opposed to the original which basically presented a lot missions and quests and let you decide how you want to proceed. Which at times could be overwhelming. The menus are a lot more pleasing but a tad too complicated at times. This game is a flat out no-brainer.
I was a Borderlands fan playing the game way into it's retirement. Loading up the tools on the computer to hack my character into an insane wizbang character romping around Pandora. Fun fun.
The second version seems much more an incremental version than a real full blown iteration. The graphics seem very very similar to the first. Load times are thankfully a bit quicker, the engine is definitely tighter.
Weaponry is just as varied as ever, but it is surprising they don't have a Forge or something to allow you the ability to craft some of these insane creations. More often than not you have a pile of junk to sell and you have a few stand by selections you go to.
Audio and spoken dialog is just as snarky as ever, again the same great quality that was a part of the original.
Gameplay also feels nearly the same. Same headshot mechanics, exploding loot mechanics, open items mechanics. Same vehicle mechanics. This may not be a pro or a con depending on your vantage. I think I'd have liked to see them push some new limits but it works.
Overall you should have a good play for at least 40 hours worth of time. Replayability, extended missions, new characters all should make any owners have a healthy longevity at home. For a renter I think it's also a perfect game. Get in, have a blast, kill, die, spawn, do it some more, finish, and retire it without feeling left out.
Good luck, have fun, and enjoy the myriad of things Pandora can offer.