I am delighted with the Maxx running JellyBean. I am concerned about what will happen when it is running KittKatt. I suppose they will eventually get KK straightened out.
My last phone started out running FroYo and had some issues right from launch. It worked great after receiving GingerBread. However, the phones performance was destroyed by IceCreamSandwich. The battery was coming up on three years old anyway so I have the Maxx now. Performance issues solved and a lot of great new features.