I have been using this microphone for some years both in home-studio and live situations, recording and amplifying acoustic guitars, greek folk instruments (bouzouki, tzouras, baglamas), even voices.
Whatever you put in front of this mic, you will get a decent sound.
On live situation it does what it should. If phantom-power is not available, you can go with the battery.
I got a second one to start experimenting with XY/ORTF arrays and I got pretty interesting results.
If I have to find a drawback, I would say it is a bit heavy. For this reason, if you are looking for two low-price microphones especially suited for stereo-recording, go for Rode M5: beside the fact that they are sold in matched-pair, (this could be not-so-crucial for you) they are a way lighter than M3 and you could avoid some hassles with the mic-stand and the need for counterweights.
In summary, M3 is a sturdy, well-built, good mic.
At this price point, the M3 is a great product.