A step down from the original.
Riptide is missing much of that. I'm not convinced it's the developers' fault. Much of what was in the original is in place here, but perhaps one simply grows inured to the game over time because the same gimmicks didn't really work this time. The screams didn't frighten me. The overlooked zombies didn't shock me. The new weapons didn't thrill me. Too much of the game was cookie-cutter simple for my taste. Side-quests were inevitably a random npc perched on high above a horde of reaching zombies. You took out the horde, and they thanked you and gave you a small reward. After doing the same thing a dozen times, it ceases to work on you. In the same way the incredible Dragon's Age abandoned the story in its sequel, I felt like Riptide did as well.
In short, if you're a hack n' slash gamer that enjoys the violence, the power, counting your gold and your level, I suspect you'll love Riptide. If you're a player who enjoys character and story, who loves the backdrop of Borderlands as much as the actual gameplay, you could probably pass on this one. The excitement and fun are simply missing in the sequel and there's very little that's new.