Since the introduction of electronic fuel injection into dirt bikes in 2008, the dirt bike industry has changed for the better. Suzuki was the first to come out with EFI, however all the hype didn't live up to its expectations. The bike introduced more problems than it did strong points. In 2009 Suzuki, Honda, and Kawasaki all came out with an EFI bike for their 450 lines and completely revolutionized the dirt bike industry.
Honda really capitalized on the opportunity to change, improving on what was already a great bike. They drastically improved on their handling and suspension, put more power where you need it, and made it easier to start in both hot and cold weather. The CRF450R doesn't utilize a throttle, so just give it a good kick, and if it doesn't start on the first kick, it's almost certain to start on the second. They improved their steering damper to set off the jerk of the handlebars from the previous model.
If you're looking for a bike you're going to feel comfortable on right away and doesn't have a lot of extra bulk for your boots to get caught on, the CRF450R is the bike you're looking for. Regardless of whether you're five or six feet, the positioning of the seat and handlebars is likely to win you over right away. If you think you like it then, wait until you feel how smoothly it handles anywhere you expect it not to. This attribute wasn't as good last year because they didn't allow the front end to push enough, but definitely fixed it this year.
Honda has also improved their power distribution, as last year there was just a lot of low end power, this year there is much more distribution all the way from low to high end. You either loved last year's model and the way it handled or hated it. They were looking to improve that this year and find more of a common ground, and hopefully stumble onto something everyone really liked.
This is definitely an all around bike that can be rode in several different types of terrain; all do to the new action of the forks. Lastly, Honda listened to the feedback they received last year about the handling and even noticeably improved that on this year's model.
After reading reviews on the bike and seeing the spec's, I sold myself on it. It's going to be a hard 450 to beat this year. In a nutshell, Honda made their 2010 model feel much more stable which translates directly to the rider's confidence in unstable spots.