For me, Mp3 is the perfect way to access my music collection. Unlike emil_greer, I only see the CD as the way to get the music into my collection legally, but which I then proceed to rip onto my hard-drive. The CD is then stored in a big box in the cellar with the rest (saving a lot of shelf space in the bargain), but I feel that to support the artist I should buy the embodied carrier. Second, and as important, the CD serves as a back-up copy against the possiblity of losing the data in a HD crash.
But I have come to appreciate the comfort of listening to my music digitally without ever having to change discs. When I buy a music CD, I see it as buying a license to listen to the music I like, however I like to do it (so copy protection infringes on my customer rights of fair use). BTW: The license to use (hear) the music is also embodied in badly scratched, used CD's, so buying those, and getting the music off the net is perfectly acceptable. The artist has gotten his profits from the original sale, and probably from the former owners' replacement as well. OTOH, buying a CD, ripping it and then reselling it, is not.
When played back over my stereo, and sampled at 168 kbps, I am unable to hear any difference between Mp3 and the original, so the comfort of being your own radio station by selecting your collection (or part of it), clicking shuffle and thereby ensuring musical entertainment for hours without needing to give it further consideration, not having to stop what you are doing every 45-74 minutes to change discs greatly expands on my listening pleasure. The act of putting the CD into the player emil_greer describes, holds no special meaning or pleasure for me.
The other argument made above still applies, of course. MP3 is a great way to sample new and unknown stuff from the comfort of your own home. But remember: Delete what you don't like and buy what you do, everything else is theft. Support the music you like. Resist efforts to restrain you in utilizing your rights.