There is nothing really wrong with the Lightning. It's a really interesting bike. It has a heavily massaged Sportster motor, but the rest of the bike is Buell, from the ground up. It's very short wheelbase, and with a low center of gravity, due to the fuel and oil being held in the forward frame and swingarm, respectively. The thing that looks like a tank is the airbox. It's belt drive, so no chain maintenance.
I have a friend who has one, as well as an 1125R, its big brother, and he loves it as a great around town bike and commuter with razor sharp handling. He basically checks the plugs and changes the oil. It is air cooled though, so it's not a great bike for riding in heavy traffic in hot weather. He also suggests the race ECU, which gets rid of the dip in power due to emissions tuning, but I had to put a Power Commander on my Kawi 650r after putting on a new exhaust for the same reason, as well as to get rid of backfire.
For a street bike, it's got excellent handling, which was a trademark of all of Buell's bikes, except for the Blast, which was a bastard child that Harley forced him to build, and which he disowned when they dropped the division. He is doing some excellent work now in his new company, and the new 1190R is a work of art and engineering.