It doesn't provide nothing but grief, in my opinion. It is natural to fail sometimes even in things you are good at. It makes a story believable and interactions deeper.
As for the combat, the only remark I'd make is that critical misses matter. Because 95% to hit is not 100%. This auto-miss detached from your stats also makes fights unpredictable in a healthy way. May be it itches the nerves of min-maxers and save-scummers but for me it makes the game fun. Extra effects for crit misses would be nice though. If you hate crit misses, play a halfling
