Some people will bring up transmission issues with the 2006 and earlier, however, their are many that have had no issues at all. Mine is a 2004 with 73K miles on it and runs and shifts great. I had it on a dyno a few months ago, and it made the same power as it did 4 years ago. The Rocket isn't for everyone, but mine has been great. I do have to replace clutch plates soon, but after 73K miles, I'm not complaining about that.
The biggest difference is the amount of dealerships, and dealer support. It helps if you have a dealership with a competent service department. Also, parts take a while to get in sometimes when you need them.