one thing that i like about dot mobi is that it's comparable to .biz and .info because it's familiar. but it's neutral about it's meaning, which gives it more flexibility than .biz and .info. There are more dot mobi domains for sale on 4.cn than .biz and .info (from my observation at least) and there is a decent amount chinese sites on dot mobi, so it's not perceive in the same way as new gtlds at least. It's more familiar. There have been a few numeric and letter .mobi sales this month, so there appears to be a buy out of sorts in development....but still has a long way to go.
No promise about the dot mobi becoming liquid anytime soon though, but who knows....