I've put about 1500 miles on my Trek Soho, which uses an IGh with the belt drive.

I am generally enthusiastic about it in bad weather because I hate cleaning a chain. Sure, I know it "only takes 5-10m", but every day or every other day that adds up. and then if you forget...

But after riding it for that many miles, I've developed a handful of complaints:

1. The Nexus just doesn't have the gear range I'd like, especially on the low end. I'm big and there are hills on my commute, so it's a problem. I'm sure a Sturmey-Archer would be better.
2. Because there are only 8 gears, it's harder to find just the right gear. I usually want to be somewhere between 5 (direct drive) and 6.
3. Changing a flat on the rear is a real nightmare. Maybe with practice I'd get better at it, but it took much much longer than a typical setup. Part of the problem might be the drum brakes.

That said, another positive is that the bike is mostly silent. I can only get it to make noise if I pedal backward. If I didn't have any hills on my commute, it would be near-perfect. Or I guess I could lose 50# and the nit would be the perfect bike :-)