I loved my 3GS, love my 4 even more. I use the extra features daily (in-built HDR, higher quality camera, faster data connection, wifi hotspot, longer battery life.
There is NO information about the next gen iPhone. Anything you read is pure speculation.
Personally, I'm expecting a dual core SOC, larger screen(4" please!), and there's a slight chance of a 4g connection. Oh, and iOS5, hopefully with an untethered JB to immediately follow.