I've had a Bonneville America since 2002. Except missing a few months riding because of the war thing, it has been out a bit. Few thousand miles. Not one problem except a slight oil seepage from the top of the gear box cover, mostly at over 80 miles an hour.
The length is longer than my 73 sportster. Stock I had no problem in the low end beating most everything off the line. The high end stock, based on the final drive ration, was a bit weak -- comfortably around 80 unless you really redlined through the gears. Although I did 105 on the freeway. This is the 790 cc model and somehow they lost a lot of HP when they built this into the Bonneville America. The stock gear ratios top out too early and you have a tendency to search for the phantom sixth gear out past 70 or so (unless you rev it high through the gears).
Stock mileage is about 44 mpg at 75 mph. I swapped out to a 19 tooth counter shaft sprocket and the mileage went up to about 48 per gallon. More importantly, you suddenly get a whole range of gears. There is some loss of low end torque, but that is probably something you can make up with more modification.
I have Triumph Off Road pipes that are nearly straight thru. It now sounds VERY similar to what my 75 Triumph sounded like. And to counter what someone else said, we sat head to head with Bonneville and Sportster and there is no way the sportster drowns it out. It isn't outrageous, but it is a good loud rumble.
I took it to Smoke Out West and we put 1600 miles on it in 5 days. Rain, shine, (more rain), freeway, highway, not ever a problem. And performance isn't a problem. I seems to have a sweet spot at about 85 mph and, after the mods, I have a problem keeping the speed down on the freeway.
There is a lot you can do with them, but I'm pumping money into some other bikes, so it isn't the priority. But it is the most reliable.
A guy once got off his FLH at a restaraunt and walked past the entrance and walked down the street to come check it out. Tell me that's ever happened with a honda.
I would say it is the best value in a new bike, but you do have to make some changes to get going in the right direction.
Hope that helps.
Snake