I am on my second GT.
The first bike had the 'egg beater' effect from the gearbox / drive that was common to the first edition of the bike. The bike would also clunk sometimes. I can't say it overly bothered me over thousands of miles.
My first bike had the usual water pump leak (early models) and the radiator cap replaced (several BMW bikes) along with new nearside switch gear (several bikes in the BMW range) but not the failure of the starter button switch. The bike always pulled to the left and overheated due to accumulation of muck in the area of the radiator's lower third. It drank a bit of oil; some of the early bikes did, some didn't.
What he said
My new bike has none of these issues, though I am sure it will overheat eventually if I don't keep the radiator clear. None of the problems put me off buying the second bike at all, nor did they ever put me off riding the first bike. What else? My latest bike has the keyless ignition, which works very well with the central locking. It also has the hill start, something I thought might be just a gimmick but I now find really useful, used like a car's handbrake.
The rest is probably well known: Great power, fantastic handling along all sorts of roads from motorways, to twisties, around hairpins, down small gnarly country lanes, in busy traffic. Good luggage. All day long comfort. Tidy ergonomics. Plenty of weight at 320 kg. Buy and above all use with confidence.
PS I have never seen 50 mpg.
What he said I am on my third GTSE and I love 'em. The latest iteration of the gearbox is nice and smooth, how it should have been from the outset. Go for it