When you listen to music through Grado headphones, it's much more of an event than just a casual listening experience...that's the best way I can describe it. You get audiophile sound at an affordable price, and the models I've tested outperform the competition in their respective price ranges. The amount of detail you hear in the vocals, panning, and instrumentation is a little startling at first...but that feeling soon turns to pleasure and you just don't want to take them off. It's also hard to go back to other brands once you've listened to Grado. It would be like getting a new 52-inch 1080p Plasma TV and then having to go back to your old 40-inch 720p unit...not to sound like an arrogant snob or anything, but it's kind of painful. The technical explanation for Grado's sound is "dynamic open-air, supra aural, high fidelity", which means that air does pass through the cans while you're listening. These are not noise cancellation headphones by any means, and someone sitting next to you would hear some sound leak even at lower volume, but it feels like more of a natural experience to me.
The "iGrado" is the least expensive model in Grado's Prestige Series, and they retail for about $50. This price is ridiculous for the quality of sound you get, and when you compare them to other brands in that range (believe me, I've tested just about everything out there) the iGrado is simply the best. I also listened to some of Grado's higher end models first, and I was expecting a major drop off in sound with the iGrado's...but there really wasn't that much.
The iGrado is also Grado's newest product, a street-style design for the portable market with an over-the-ear loop/behind-the-neck fit. I've tested numerous different headphone brands that have this same style, and most I found to be very uncomfortable, digging into my temples, or just too damn tight. This was my major concern with the iGrado's when I first saw the pictures...but then I got them in the mail, tried them on, and they fit like a dream! They have nice ear cushion, no temple digging, and I really don't have any complaints with them whatsoever.
NOTE: Belkin and Dynex make microphone adapter cords with pause/play/skip buttons too, if you want to use the iGrado headphones with your mobile phone to talk or listen to music.