These earphones come with three different sized rubber ear pieces. This means that they should be suitable for any ear sizes. However, after trying them out, I have to say I find my original iPod earphones more comfortable to wear. On the plus side, the sound quality goes some way to make up for the discomfort (which isn't terrible, I might add - they just feel slightly funny!)
These earphones give great sound quality over all ranges - from bass right through to soprano - without a hint of distortion. The same cannot be said for my iPod earphones which sometimes struggle with bass sounds, particularly when the volume is rather loud!
This product also comes with a handy carry case to store the earphones when not in use, which I find extremely useful as the wires don't end up getting tangled up in everything! It does look as though the plastic hinge may snap after a prolonged period of use, but for now, it's a very good idea. Overall, I'm relatively happy with these earphones, which do the job they're designed to do, albeit with a slight discomfort for me anyway.
UPDATE: I feel I must add to this review regarding customer service of the company. I managed to lose one of the ear cushions, so I contacted the company asking how I could manage to obtain another set. I was fully expecting to have to pay for them, however when I got a reply back the following to say that a pack of 10 were on their way, I was absolutely shocked! So, customer service at Logitech certainly know how to impress!