I  just bought Dr. Zed's Zombie Island (or however it is titled) and the Underdome DLC add-on today. 
I've only gotten to play through the first one, Dr. Zed's, but I really enjoyed it.
I really enjoyed the tone, atmosphere and presentation of this add-on. While I didn't find myself scared or anything or threatened to go around a corner I really enjoyed the creepiness of the whole level. I really dug the choice in colors, the forestry and the old American Haunted house look of the buildings throughout the level. I liked the little touches of the jack-o-lanterns as well if I was a kid I would have felt a little more threatened. The only thing I could hope for would be that they could've made the maps a little bit more darker but it is a comic styled game so the brightness kept that flavor intact and didn't detach itself away from the vanilla title. The music was pretty good it really kind of captured the whole idea of being alone (for the most part) pretty well. 
 
I'll start the Underdome tomorrow.
 
What are your thoughts on these Borderlands DLCs? Like em? Hate em? Why?