Depending on what you want to use the pistol for. For most shooters, any RDS can improve accuracy, target acquisition and speed. So it's good for both range and competition (provided RDS are permitted). They are not as reliable as iron sights (you either have to worry about turning it on and off or washout) so it's not something you should be counting on in an emergency situation. Lastly if you are an operator operating in operations, then go for it, because RMR is hella tactical.
I just recently got an RM07 for my FNX Tactical. It's awesome. It can actually get too bright, but I haven't had it out in the sun yet. The lowest setting is nice for a small dot at night. And it runs forever on one battery, so I don't worry about turning it off unless I'm putting it away.