How in shape are you? That's really going to dictact how comfortable the bike is for you on long rides. Personally, I'm young and in pretty good shape and rather enjoy the comfort of the bike on long rides. 300 mile days are not a problem with the stock seat. Even with the wide rear tire, the handling is surprisingly good.
However, the springer fork has a bit more travel than the hydraulic forks and can create a bit more vibration on uneven surfaces. If you are looking for a bike that you use mostly for longer trips, it may not be the best option. If you're looking for a bike that you cruise around on and occasionally throw bags and a windshield on for long trips, you won't be dissappointed.
The thrill of riding this bike and all the looks you'll get at gas stations and stop lights clearly makes up for a few minor comfort issues.