I've used the Neo for a long time, and I'd say the pros and cons.
These are all my opinion, based on my usage since Sept '08
Capsule Neo
Pros:
-looks nice
-won't scratch your iPhone because of the silicon membrane
-will really protect your iPhone (saved mine quite a few times)
Cons:
-adds bulk
-if you have the white, it easily stains. if you have black, the I-frame chips at the sides according to majority but mine hasn't yet
Btw somewhere in this forum there is a discussion thread about the same topic you posted...