I was never in any hurry to buy this game seeing as i already have SF4 and have played it to death some time ago. However, the more i read into Super Street Fighter 4, the more i think i may actually go out and buy it...
I bought it and I have no regrets =D It's an awesome game made better, and the new characters really add to the gameplay. I only use Cody/ibuki now and their both new characters =D.
If you're a fan of beat-em-ups then i urge you to get it, no question. ASDA were selling it for just £20 the other day and the RRP is only £30 - it really is worth twice the price in my eyes, and i don't say that about games very often.
If you're not a fan of fighting games, i would urge you to atleast hire it anyway as it really is as close to a perfect game as you can get, matched only by Street Fighter II