I have had my m50x's for 7 YEARS, since I was 15 years old, and before I knew anything about audio, music, or much of anything else. The fact that I still own them astounds me given my track record, so I've decided to provide a review for the regular everyday consumers out there still considering these bad boys.
1. Style
Just look at the pictures mate.
2. Utility
These things are pretty portable, not too heavy and they fold up well. On top of that they come with a removable cable which is very handy, and 2 alternative cables, one longer, and one coiled. They come with a pleather carrying pouch that is good for any long distance travel, although it doesn't provide much protection.
3. Comfort
These headphones aren't too heavy, and the padding on the headband is sufficient, unfortunately over time it has worn and long listening sessions can hurt the top of your head a bit. The pads are a little bit of a weak spot, they're not very thick and eventually had to be replaced, but again this is 7 years of use from a teenager, so grains and salt and all that.
4. Sound
The M50x's are what you'd call 'V-shaped', meaning in this case that they have MUCH more pronounced bass (BIG 808'S), some more restrained and less clear mids (vocals and the inbetweens), and quite a sharp treble (high hats etc). I would consider them a 'fun' headphone. In the audiophile community there's a pretty common opinion that neutral sounding headphones are in some way superior, but we normies know that it's great for your music to have some punch (in this case a complete haymaker). I've always loved the sound of these headphones and I genuinely still do. The seal is decent, but if you're cranking your gabber on the bus like a degenerate there will definitely be some sound leak.
5. Build Quality
Now given that I have owned these for so long you may be led to believe that the build quality is quite good, but honestly it is pretty poor. These headphones are completely plastic (besides the pleather headband), which makes sense given the price. The earpads are cloth covered in pleather, which after about 5 years had completely peeled off. The cables provided are thick, but I had a persisting issue where the jacks of the cables kept bending and snapping, so be mindful of that.
Conclusion
The Audio Technica M50X's are a great pair of cans, and I've listened to them almost exclusively for a long time. I have to keep in mind that the issues of parts wearing is more to do with the sheer length of time that they have been my daily drivers. If you're looking for a pair of bass heavy midrange headphones then there's not many that can match these.