Our 5050 has been faultless since we got it new in 2009. 4500 hours on it now. The only problem that we had with it was that the alternator fell apart about 3 years ago and a new one was quite expensive compared to alternators for other tractors. Ours has a power shuttle and it has not given a bother.
If I want to find fault with it, it's that it's 97hp, but a very light tractor. Yes, it's easy on ground and very nimble around the yard, but you need an extra bit of care with a heavy load behind it such as a dump trailer or tanker.