I wrote the following on another forum, but this is a good place to repeat that analysis, since this is the M100 review and questions were asked about a good closed headphone for general listening. The last sentence, saying the M100 can be a good listen with EQ, but not a relaxed listen, is best explained in Edd's review.
I have the M100, Momentum, and P5 now. Not much of a really good comparison possible, since the basic signatures are so different that speaking about clarity or other fine qualities, those qualities are dwarfed by the much bigger differences. My personal quick summary is P5: Pretty neutral, very slightly tilted to the right (warmer, softer highs) from flat or neutral. Momentum: Bassier than P5, richer sound overall (makes P5 sound bland by comparison), but very slightly more HF rolloff. M100: Very bassy, makes mids seem recessed. Slightly uneven highs can make some material sound brittle or glassy. I think the P5 and Momentum are good all-arounders, the P5 more for the conservative purist and the Momentum for the person who doesn't care about purism or whatever and wants to enjoy its richer sound. I can't advise on using the M100 played flat, since that's basshead territory where I have no expertise. But with some bass reduction the M100 can be a pretty good listen, but it won't be a relaxed listen, if that makes sense.