I have an '08.5 and do have some complaints with the MP3 capabilities.
- I have not yet figured out how to quickly skip to the next song when using the random feature. Most MP3 players assume when you hit 'next' you want the next random song -- the MS3's unit (at least my Bose) jumps to the next file in order; for example, you're listening to file 23 and hitting 'next' takes you to 24 and subsequently disables random. You can simply hit the random button twice which disables random, re-enables random and jumps to a new random song. Eh...
- I have found the MP3 system (again, at least on my Bose) to be very particular about the ID3 tags on MP3s. I've used two different ripping programs (and did some testing), and at least for me, ID3v2 tags work... but if I EVER edit the ID3v2 tag, neither the ID3v1 or the ID3v2 can be read by the system -- and subsequently no song information will be displayed inside the car. I am using WinAMP to edit the ID3v2 tags -- which could certainly be the problem. All that said... if you rip MP3s with ONLY ID3v1 tags, you don't have anything to worry about.
- Similar to the previous point... the LCD display can only display 12 characters which limits how much of an Artist/Album/Song Title can be displayed without 'scrolling' but this isn't ultimately a problem with the MP3 capabilities.
In the end, however, having MP3 capabilities is a very nice thing to have and these issues wouldn't keep me from deciding between having and not having the MP3. Of course, with the Aux jack with the addition of an iPod, etc... MP3 capability isn't as necessary. Hope this helps...