I had a Q9450 before upgrading to the i7 x980. I wanted to see if there really was a big difference and to for once buy the no kidding top CPU. As far as I can tell things are faster, but really its only on things that are multi threaded. I tried out a few games so far and ones I thought were multi threaded were, but it doesn't show up as using more than one core. So its a bit of a mixed bag. Multi-threaded yes, but not necessarily across multiple cores that Ive been able to see. Doing google searches for multi-core games hasnt really helped much. I have more research to do.
Is it fast? Yes. Can you tweak the speed up and down easily since its unlocked? Yes. Its also pretty cool (heat wise) which is a good thing. Im using a DangerDen waterblock and it stays a pretty constant temp.
Does it really really matter having 6 cores vs 4?...not that I can tell. Its like driving 200mph on the highway, then saying 'hey I can go 215'. Either way, its plenty fast and well beyond what is needed. Im sure there are folks out there that do a bunch of video editing, or actually use photoshop for their work. For them, yes I can see this as a smarter buy...if you actually use this to make money, or to time what you are doing.
I would probably say that its smarter to buy a new SSD than a CPU like a i7 980 if you want to see big performance gains. A Crucial RealSSD-C300 SATA-III 6Gbps SSD for instance would be a pretty big improvement to most people's systems and give you extra cash to get a non extreme CPU.