S3... Still worthwhile?

I'm itching to upgrade from my Iphone 4 and my upgrade date is tomorrow. Right now there is a deal for an upgrade a line for 30$ online, plus you get two flip covers. My question is, will I miss much from the s4? Will be s3 be supported with updates for the two years? How much of an upgrade spec wise will it be from my 4? I've had it so long I forget lol.

Im mostly considering this route because 200$ on a phone right now probably won't happen, but this deal is pretty sweet.