I've used two pairs of Beats headphones and disliked both. I guess the best way to describe it is that they sounded non-neutral... they change the audio.
When I try stereo equipment I have a few pieces of music I always return to and I know well, my reference points. I, and most audiophiles, shoot for equipment that is as neutral as possible, that introduces nothing new into the recording whilst reproducing the recording as faithfully as possible.
If you're asking audiophiles what equates to good, the answer will be neutrality; not modifying the audio at all. Usually this means introducing no warmth where there was none, no harshness where there was none, emphasising nothing that wasn't originally emphasised in the recording and studio, etc. You shouldn't hear the equipment used for reproduction in the music that you're reproducing.
Beats headphones are a bit like a Mega-Bass switch on old Walkman systems. What they do to the audio isn't enjoyable if you tend to like things with acoustic sections, folk music, classical, jazz, and rock.
But... for House music, Hip Hop and other club beats the changes may actually be something you enjoy and seek as they reproduce an element of how you enjoy music (closer to the memory of the club, or a loud car stereo than a perfect recording).
They are crap, for want of a better word, because they change the music noticeably. But you've got to realise this is super-subjective stuff as some people want those changes.
They are also crap, probably the right word this time, because the material choice at this price point is pretty dire. But hey, they made plastic a luxury thing again, you could argue there's some brilliance there too. Most issues around durability come from the choice of materials.
As to whether they're crap full stop... well, no.
If you like the big beats of clubs, reverberating bass that dominates, and you rank the iconic fashion statement above durability (because fashion isn't designed to last anyway)... then Beats aren't a bad choice.