The only problem with them is the earpads suck, and they're not cheap to replace. I made my own out of foam rubber. Bit ghetto but they work.
I wouldn't say only problem.
To me, Grados are just as bad as the Beats (or similar thwompy bass headphones), in that it has a strongly distorted FR that might be good for some music, but they don't offer anything that a properly designed headphone with an EQ setting to offer that distorted sound could offer (better even, since it would likely still be able to offer better low end), and the latter will be a lot more versatile. Even compared to the Beats its a tradeoff, where you can get better sound for cheaper in the SR60/80, but the Beats are more comfortable, and you can use them without irritating everyone around you by injecting that hot treble out for all to hear.
Don't get me wrong, I definitely think they're worth a listen, especially the SR60 or SR80. Their higher end offerings are flat out embarassing though in my opinion, just more of the same sound (seriously, not even better in absolute terms over the 60/80, just somewhat different, at times arguably worse) with audiophile bling (metal or wood cups) with somewhat better (but still not very good and frankly ridiculous for the prices) earpads. The original statement headphone they made was actually quite good, offering a high end refined sound, since then I don't know why you'd bother with their higher end offerings. Plus, and maybe this changed in the last couple of years, but their customer service and quality control had also turned spotty. Then couple that with their "whiskey barrel Elijah Wood" promotion and I just can't help but feel they're doing the same path that AKG is, its quite disappointing really. I'm not even going to mention their expensive CMoy in a wood block amp. Ultimately, I can see the appeal of Grado, they're very punk rock, but they're just too flawed for me to like.
To be fair, they're not the only brand that's missing or has a lot of misses or going for gimmicks and marketing over real quality development, but few companies consistently make the same mistake over and over like the Grado lineup (mostly because they use a very similar formula for their lineup, excluding their IEMs and lineup that doesn't really fall into the audiophile category).
This new level of headphone popularity is certainly odd. We're getting both much better and much worse headphones. Seems like one step forward one step back in many ways. Luckily now, there's much more robust testing and general feedback so its easier to sort through things.