Borderlands Question

"Do the DLCs significantly add to the fun factor of borderlands?"
Yes they do. All of the dlc's have their up's and downs (i'm looking at you crawmerax..) And the one i personally enjoyed the most was moxxi's underdome riot. mainly because i love arena-esque games. Put in roughly 120 hours in the game itself, and about to start my third character (a mordecai), that also means i spent roughly 60 hours on my two chars, and they aren't even godly geared yet! If you are to only get one dlc though i'd say go for knoxx since it is the most profitable dlc (Again im looking at you crawmerax.. and bugged armory :E).

I personally rate the dlcs:
Ned 1/5 - Mainly because of the collecting quests, Nor did i quite enjoy the scenery or flow of the dlc (which you also have/get to do in Robolution dlc)
Moxxi 4.5/5 - Because i love the god damn arena! somewhat unfair rules though, but it makes it ALOT more enjoyable imo!
Knoxx 2/5 - Story-wise it's decent, i'd give this dlc a 3/5 if it weren't for the possibility to bug the armory, and ofcourse crawmerax..
Robvolution 3/5 - First 5 quests you encounter for tannis is a complete god damn grindfest, the rest of the dlc is okay, and the final boss was a decent challenge, Overall i enjoyed this the most other than moxxi's!

YOu MUST buy the armory of GEneral Knox. I played that DLC more than the acutal game. And Moxxies Underdome is also great because it is a giant monster arena. I did not like The zombie one because it had to much quest where you collect one item 50 times to get another quest.

I'd recommend buying them all. Borderlands' DLCs are more valuable then the most DLCs you see these days.

All DLCs are awesome, they add an unspeakable amount of good stuff.

The dlcs are worth it.

buy the GOTY, worth easy