It's a very nice servo for the money.
My son and me flogged three of them all summer without issue.
Compared to premium servos (e.g. Futaba BLS551, Futaba S9551), which we also have, the Turnigy 1251TG:
--- Has a little more gear slop.
--- Output shaft is a tiny bit under-sized. I addressed by making the inside of the servo horn a little smaller via a tiny bit of thin CA. Let the CA dry, then install the horn and it's nice / snug.