I'm eligible for an upgrade on Sprint and currently having trouble choosing between the SIII, the Note II or waiting for the S4 to come out next month. I've played with the Note II in-store, and my mom has the S3 and still can't decide.
Unless you are absolute need for a new phone right this minute I would suggest waiting to see what the s4 has to offer. I love my s3 but would for sure wait to see aha at the 4 has to offer.