Down in the (currently stormy) GOM, the 139 seems to be getting mixed reviews (all secondhand, I'm a 120 pilot). Pilots like flying the aircraft, pax like the ride, and so far in the pure performance arena it is doing as advertised.
But (you knew it was coming)...
Reliability has been an issue. The 139 wasn't offshore-ready when delivered, and so it is a game of wait and see what breaks next. Avionics are the biggest issue. Of course there are the ADs which (unfortunately) are to be expected from any new buildup (the 119 went through the same evolution - now it is a reliable performer).
I suspect a year or so from now the 139 will be universally liked in the GOM, once the teething pains subside.