I find it perfect. I don't really have to push it, thus reducing vibrations - I can rest my finger on it, and all I have to do is flex my finger muscle a bit when I want to take a photo. This implies quite a bit of accidental shutter tripping, but I find I can shoot it and get good results a stop slower compared to other rangefinders where I really have to push the shutter release (Yashica GS, Minolta 7s, etc).
It has to be said that it varies a lot from XA to XA though, age and condition are important factors - when not taken care of, the shutters tend to become irresponsive when old, while a very new one, or self-adjusted one, may be a bit too easy to trip.