Pros: Portability, ability to take any music thrown at it
Cons: initial comfort, stock pleather pads cause sweat issues
These headphones are great. I listen to mostly metal and have listened to Grado's mostly because of it, and these phones are really similar to the grado sound; I can see why people refer to these as the equivalent to a closed grado headphone. It's funny to me how different these phones are to the description of every other sennheiser headphones. Every review for the hd 600 or 650 talks about their laid back nature, while the hd 25's are anything but laid back. indeed, they are very forward, and for metal and rock, this is just what the doctor ordered. Bass-y music sounds great too, these headphones can really bring out the lower end of the sound spectrum. My only gripe with them is the initial comfort - it takes a bit to get used to the amount of pressure they put on the ears. After owning them for over 3 weeks now though I can say that I love this set. While its hard to argue with the portability of IEMs, these guys just sound so good I am willing to give up a little more space in my backpack when i need to store them.
Highly recommended, especially with the velour pads!