I have an '07 M6 and it is amazing. If you read some of the posts on here, you'll know it can ALMOST keep up with a 335
. One thing you will notice is it has very refined power. You hit 80 and above without any drama, it's just smooth and powerful.
One drawback is attracts a lot of attention. I can't go into a WaWa without some teenager putting his hands all over the windows trying to look inside. Another drawback is that it seems that it brings out the "dick" in other fast cars. I can't stand when some GTO, WRX or 335's (sorry, but 335's do it the most) get next to me and start blipping their throttle to egg me on for a race. I just want to drive in peace.
I promise you though, the pros outweigh the cons.