The way he's gone about it is daft and disrespectful, I'd be pissed off with him if I were a Liverpool fan. He should have kept his mouth shut until the end of the season then quietly said he wants to leave if a decent offer comes in. He;s going to have a rough ride next year if Liverpool play hardball and no one matches the fee they want.
But I don't have any problem with him actually wanting to leave. Whatever Liverpool's past, I don't think anyone can realistically argue that he's not more likely to challenge for major honours, improve his own game in the CL and be around better players with someone like City.
Don't get the 'he should stay at Liverpool where he's guaranteed to play' angle, he'd likely start most games for City and he should have the confidence to back himself to do so, and go on to be a main player for them, not worry that he won't step up to the plate and so not even attempt to.
There's clearly more incentive than just money for hm to leave.