I dont have the 5700 but I do have the 4500. Not the same camera at all but the same generation of Nikon's. I'm happy with it.
If you want some good info on the 5700 go to: http://www.dpreview.com
They're online forums almost rival this one (the devil you say!) as far as good info, and they do really detailed in-depth reviews. Heres the review for the 5700.

Let us know what you decide.

Z~