I've been on NuvaRing for almost 2 years and I've had no problems. I've had no weight gain or mood effects. My periods have been lighter. Even with some lighter training in the last two years (due to grad school) I've run a couple PRs and overall respectable times. I do remember thinking that my breasts got slightly larger when I first started.
I can't comment on the level of fatigue since I moved at about the same time I started NR and consequently changed from running mostly on packed dirt trails to pavement. I had a harder time keeping up the mileage but I think that was a result of the surface and grad school obligations.