I agree with arn here, the DRM is remarkably similar, and the limit on playlists is minutia. The subscription option is a nice option. although I, myself, would not use it, it's just another way to make money. However, it opens the door wide open for hacks to proliferate huge volumes of ill-gotten music. As one poster noted already, I don't think it'll last long once the reprecussions are realized, much like the internet sharing option in iTunes.
SpyMac was making a big deal about promoting the abuse of that iTunes feature, and now no one gets to enjoy it. Thanks *******s. That really makes me mad, the one time I took advantage of it I discovered some music I really liked. Thanks again, guys!
AAC is a big factor, I think, that has been largely ignored here. Are these other services selling 128-bit MP3? If so, they're ripping their customers off. MP3 sounds like crap, which is why, until iTunes 4, I never got into ripping tunes onto my computer, because at a reasonable bit rate, MP3 sounds crappy. AAC at 128 is really quite good. So what are people actually getting for their dollar? That's the important part.
If a store opened selling DVDAs for $13, and three others were selling CDs for the same price, if you could use the DVDA format, which would you patronize?
Plus, the integrated experience is a selling point. But I don't know anything about the Napster interface (nor do I care to) so I won't comment, except in that I know the iTunes experience is great. Howzabout Napster?
[Edit] OK, so WMA is the format of choice for this sevice, and I think the BuyMusic stupid store. So how does WMA compare with AAC? If it's anything like WMV vs. Quicktime...well, I think that analogy speaks for itself...