I just returned from my local track after a great day of riding. The new YZ is a way different ride from my CRF250R (which I still love as much as ever, BTW), possibly the most intense bike I've ever ridden. Both bikes are the same weight, but the 2 smoker has less reciprocating mass and a lower cg, so it feels lighter. Basically, it feels like near-CRF450-level power w/ sub-250 thumper weight!
First, the bad...the extra power makes clearing jumps that much easier, but the faster landing speed + no engine braking made me go really wide (almost off the track) on some turns right after landings. It's also a bit more tiring to ride due to all the extra power + an overly light flywheel which means the bike revs practically just by looking at the throttle (a heavier flywheel may be my first mod, not counting the normal change to a real chain). All stuff I can overcome, just have to adapt my riding style after the last few years of riding nothing but thumpers.
The good...it combines the best attributes of a smaller bike (light weight/tossability) w/ all the power you could want and more. It wheelies REALLY well! It handles whoops better than anything I've ridden, and falls into tight corner ruts really easy. The suspension is pretty impressive...I didn't expect much based on an '03 YZ250 I recently tested (which was much harsher than my CRF) and the showroom "squish" test, but it worked great on the track and I never even thought about playing w/ the clickers.
This is coming from a guy who's been a hardcore thumper loyalist until very recently. I've really dug the late model YZ250's I've ridden, and was thinking I'd like easier maintenance, more power w/ no weight compromise, and less worry about grenading my engine. Can you tell I'm excited???