should I wait for this to come out or just pick up the first one? How are they?
Depends what races you want to play. The first one is great, probably my favorite total war ever and this is coming from someone who didn't even buy it until it was ridiculously on humble bundle because Rome 2 was so shit and I had absolutely no faith in CA after that.
2 is really just an expansion, an expansion that has as much, if not more, content as the first game did on release. Except it's looking far more refined and unique.
If you want to play one of the races coming in 2 I'd say hold out for it. If you really wanna play a race from the first game you could give it a go.