I thought that it was soon, ad this caught me by surprise but I am happy for its release. I think that GameFreak knows what it is doing, and I think that the game will have as good, if not better the quality of its predecessors.
I have to admit I'm surprised by the sudden release of this generation, and I'm a little worried that the games are going to be rushed as a result. I do feel that they need more time to develop the games than what they're giving themselves for them to be of good quality, so I'm concerned that X and Y might take the annoying "style over substance" approach and be all pretty graphics and nothing else, like about 90% of console games these days.
Although I'm not really prepared to categorically say it's too soon for this generation until I have the game in my hands and I've seen what they've done with it. If the main game is shorter, or they've cut content (i.e. not being able to completely fill your Pokedex, or a smaller region, etc) then I'll say whether or not it was too soon for this generation. The gap between Gen I and Gen II was quite short, and to be honest I think 2 games set in Unova was 1 too many, so I'm eager to move on from that. I just hope they do a good job with it. If they do, it wasn't too soon for it.