The M361 is a very good drop-in.
As always, it depends on what you want.
It cannot put out larger light output than it has on max, and although its throw is decent for what it is, you would need to get to different drop-ins to get more throw.
Also, it is not the most efficient, if you are willing to use the light output from a single output drop-in, it should be more efficient (longer run-time for same batteries and lumen output).
Personally I don't have problems with either the UI or the PWM so don't count those as reasons to prefer other drop-ins.
But for general use, etc has posted many times how useful a drop-in it is, and how it can replace several other drop-ins.
It is a relatively new addition, so for many previous years many users got several drop-ins, and you could sort of do a bit of house-cleaning by replacing a few of those with the M361.
I like it for travel, in a compact 2x123 primary battery tube. I don't bother using a 1x18650 (or other Li-Ion) rechargeable when traveling, just carry a few extra batteries.
It is a bit of an outlier in terms of voltage range, as archimedes mentioned, so you have to also see what you have for a host and make sure it matches.