Pros: Quad core, Overclocking capability, Bang for buck, durability
Cons: outdated, temps, TDP, max temps
You could usually hit between 3.2-3.6ghz depending on your motherboard, those P45 motherboards with this chip was a match made in heaven, obviously it required a SLACR (go) batch Q6600 and a low VID, but if you get lucky you could even hit 4ghz.
Unfortunately because it is old and there have been many new releases, 1366 1156, 1155 and now 2011, it is quite hard to recommend it, however if you do own one already I would always say don't get rid of it, keep it as a backup rig, this was truly one of those chips that could take a lot!!
The max I could hit with my Asus P5E motherboard (flashed to Rampage Formula BIOS) was around 3.9ghz, however I couldn't stabilize it, the VID on my chip was a little higher than most (can't remember) and the motherboard FSB restriction didn't exactly help.
I did eventually keep it at 3.8ghz with 1.6ish voltage for over 4 years without any problems, this is certainly a touch cookie and one that will never be forgotten!!!
10/10 Q6600 FTW