Knoxx had some real warts though that people tend to forget about. The highway sections were obnoxious and filled with back travel time padding. Enemies tended to just instantly gib your shields yet took a ridiculous amount of punishment themselves against most guns/elemental types. The real saving grace was decent writing and the big lootfest that players had been expecting since the game came out.
Borderlands DLC in general was really iffy, I am "passing" on a seasons pass for that reason.