The best DLC. General Knoxx is a great character and the writing for him is great, plus the Crimson Lance provide a challenge in this DLC that's missing from much of the rest of the game. And Crawmerax, the level cap rise, and the armory itself.

Interesting, but a bit cluttered. I tried a couple of different specialisations, but both times 90% of the items I found were worthless and I the RPG elements felt like they didn't offer much bonus. However, the use of the source engine is very fun, with spells to throw things at people, kicking, traps to drop items on people, kicking off cliffs, throwing items, and kicking into spikes. There's a lot of interesting exploration, too, but too often you'll find a cool puzzle or secret room only to be rewarded with completely worthless items. Still great fun, although I've be unable to progess past the fourth or so chapter due to a crashing error. Don't take that as a criticism of its stability, though; my computer doesn't meet the specs.

Shoot zombies. Shoot more powerful zombies. Escape over and over. Troll people with molotovs.