I strongly recommend getting bundle and beating the average just for Dungeon Defenders alone. Aside from a few end-game progression issues, it's an incredible value, especially with the extremely, extremely large amount of DLC.
I honestly did not enjoy Dungeon Defenders that much. I bought the base game and the original Orcs Must Die during a Christmas sale on steam and I thought Orcs Must Die was a much better game. The two games seem similar and at first glance DD looks better because it has multiplayer and more rpg elements than OMD does. But I thought OMD had much better core gameplay. I thought the game was just more fun. I felt like the controls and camera viewpoints were better.
That said this is a great deal if you do end up liking the game because Trendy seems to be making most of their money by releasing dlc for dungeon defenders, and I think there is around $50 worth of dlc in the bundle. I have 25 dlcs listed for the game in my steam library, and I haven't spent any money on the game besides the purchase of the base game and the humble bundle.
I'm pretty sure every Humble Bundle I've ever bought has had a "Like what we're doing? Click here to increase your order amount!" link on the download page, so they've already covered that base. :)
If only it played for 5 minutes for me. I get some obscure message at startup (I think it has to do with the format of the textures). Tried support - didn't get anywhere.
It looks fun, but the crooked over the head camera makes me sick. I mean physically sick. It screws with my sense of symmetry, my side vision and my expectations for character movement all at the same time.
I doubt raising it as an issue would mean anything, sadly. People like me must be rarer than colour-blind linux users running xmonad.