Mine works well. Some do not like the "unlock pin" mechanism.
The "unlock pin" which secures the slide and barrel to the frame similar to most locked breech pistols does not have a fixed mechanical lock. When the slide is in battery, during the firing cycle, or locked open, the pin cannot escape. Takedown requires pulling the slide open a partial amount to align a hole in the left side of the slide to allow the pin to fall out (or push it out from the right side with a pin or toothpick). Thus if you tilt the gun left side down and slowly operate the slide, the pin can come out on it's own. This does not happen when firing, the slide speed is too fast.
I can't speak to long term durability, but reliability has been excellent. I had a strange issue where a round of older hornady critical defense failed by the primer head breaking off and that little bit of brass got caught between mag and slide, preventing feeding. I cleared out this debris and continued to shoot another 50 or so rounds without incident. As a side note, Hornady replaced my ammo, box for box.
The trigger pull is typical long DAO, with a clean snap break near the very end of trigger travel. At the break there was greater force required (stacking) but this smoothed out greatly after a lot of dry firing.
I know Remington has a poor reputation because of the R51, but I really like my RM380 and it is an excellent pocket carry gun for me. My records show 316 rounds through it so far, nothing but handling and holster marks on the thin finish. When carried it is usually in a rear pocket holster, and because the frame is aluminum I do not worry about sitting on it.
