Where are you? I've had pretty good luck with Unicom 3G in Beijing, but their 2G coverage sucks pretty hard.

So far as number portability goes: they've been talking about it for years, but as far as I know there's no way to do it in most places around China at the moment -- there have been rumors that the MIIT will force operators to implement it around the end of this year, but they've been talking about this literally since I started following tech industry news in 2005.