I wanted some closed back headphones a few years ago and fell in love with DT770s in the HiFi store, just had to have that bass sound!
A while back I gave them to my daughter and immediately started missing them (only used them occasionally, but sometimes it's just the right sound, and great on trains). So I bought another pair last year and found they are not quite as good, still great fun though.
Let's be honest, the bass is really OTT on these, however a lovely sound; as others have said here, great for movies and I find for older recordings. For example they sounded really great when watching a DVD of The Doors in concert from the late 1960s.
I was pleased to see they have an appreciation thread on this forum, if I was only allowed one pair of headphones it wouldn't be these, but I won't be parted from them again!