I use these with an fully acoustic drum kit while playing technical death metal in a concrete basement.
They do a very good job cancelling noise.
However, sound-wise they only qualify for monitoring while playing drums.
The lows are very weak (which is good for distinguishing separate hits while playing though), mids are there but lack definition, and highs are even worse. Cymbals sound very poor and sometimes even disappear while listening to music compared to other headphones.
Overall, the sound quality is very compressed and dry. I wonder if the extreme isolation is absorbing something.
They feel solid in the hand, and even more solid in your head (or atleast mine).
They grasp very well. They start hurting my ears after around two hours of continuous wear, but surprisingly, after having a 5 minute break I can use them again for two hours. A minor flaw though, the "DT 770 M" plaque has some very weak glue, it started peeling off by itself after a week. Easy to glue back though.
They work for my needs, but I wonder if there are better choices for the price.
Definitely DO NOT buy these if you're a sound engineer or are looking to mix something.