What type of apps would not be a good idea to build on top of IPFS?

From @notduncansmith on Sat Apr 04 2015 19:31:48 GMT+0000 (UTC)

For example, would social type apps (Facebook, Twitter) work well, or not well? CRUD apps? What are the challenges associated with transitioning from the current mode of wrapping databases with HTTP?

Copied from original issue: https://github.com/ipfs/faq/issues/1