No, River isn't gone yet, and she'll probably be in the 50th because Moffat likes to stuff his characters into things.
If you can suffer through Series 6 (which I liked the first half of and hated
Let's Kill Hitler and its kind), I promise it gets better in Series 7 (particularly the second half with Clara). There are a lot of non-Moffat episodes and there are only a couple where I could realistically say "wow, this episode was a dud."
Despite all the issues with Moffat's writing (and it's not just him, it's several of the writers) I really have grown to like Matt Smith as the Doctor and will be sad to see him go.