I actually fell in love with the Zune Marketplace far before I seriously considered the Zune HD.
I had the biggest *click* moment today when I realized that I could just keep the Zune HD untethered forever, using Wi-Fi to grab all the content i'm interested in. I use the Zune software on my home computer and work laptop and am very pleased with it.
I did get the album artwork settled, and it turns out I simply overlooked the update album artwork option. I can set it to whatever I want and it works fine.
I am currently a PC user (Windows 7) so the lack of Mac support does not bother me and in fact i'm quite pleased its not something like Itunes which I personally do not enjoy at all.
I am currently using a Cowon S9, and have been experimenting with it for the (roughly) week that I've owned it. Its a fantastic device, but I am currently planning to order a Zune HD 32GB to experiment with. The Zune Pass has really changed how I approach music and the ability to be completely untethered and go wireless is very powerful for me.
I am excited by what Microsoft offers in the Zune HD and the Zune Marketplace. The nice desktop software is really just a perk to it all. As far as managing the content that I already have, it actually occurred to me that I could just have the Zune go find and download all of it. I have master flac archive of my music so keeping up with a 2nd mp3 archive set is not something I really need to do.
All told, i'm looking forward to experiencing the Zune