It's more Borderlands, with a slightly different angle. But there's still plenty of shooting and looting!
The first thing you'll notice is this DLC is much more vehicle-centric than the original game. The main hub area of The Secret Armory of General Knoxx is a town called T-Bone Junction. Not much more than a highway way point, your only options for travel are down the highways. The Runner of the original game is gone, replaced with a monster truck with homing missiles. Eventually you do get access to two more transports, including a racing version of the Runner called a Racer, and a military APC.
This vehicle specific aspect is okay, but some players may find it frustrating how fragile your cars are when being shot at, and how difficult it is to actually kill anything while driving. The other aspect of having vehicles in the forefront is how large and expansive this DLCs new areas are. Which actually leads to one of my biggest gripes...
There is only one fast-travel station in the entire DLC, and it is located in T-Bone Junction. Having only one fast travel station in Zombie Island wasn't too bad, as the areas were smaller and quicker to get to. But you could spend a great deal of time fighting your way to the farthest locale in Knoxx only to have to start over if you don't have time to finish what you were doing. The lack of fast travel in addition to a bug that caused a roadblock to keep reappearing, slowing your travel even further made for some tedious gaming.
There's still plenty of shooting and looting to do in this expansion. And with the addition of 11 new character levels, you'll find the best weapons and gear in this DLC. Some of the new content here seems to borrow from MMOs such as World of Warcraft. There are many similarities in how Borderlands and Knoxx are structured to that game. Most specifially a couple of the boss battles that require MMO-like strategies instead of straight-up shooting until it's dead tactics.
The difficulty is also ramped up a bit. Requiring you to have the right load-out of weapons at your disposal for dispatching the various foes. But on the same token, the humor of the game is ramped up as well. Knoxx is probably the funniest Borderlands outing to date, and General Knoxx himself is probably the most memorable character to date.
If you love Borderlands, and want more shooting, looting, and challenges, this is the DLC for you. The content here clocks in with as much as some full-blown games. And even after the final credits roll, don't turn off the console, because there's hours more worth of stuff to do!