I've said this on the WotC boards, but I'll add it here just to be the crossposting spammer that I like to think of myself as.
I'm a Mac user. I'm a D&D player. I have played in online games before, and am currently playing in one (Age of Worms via Skype and IRC). So in many ways I'm the target market. However, I can never use the apps that WotC releases for their digital initiative.
Not only that, but lets take my Age of Worms game that I'm currently playing via Skype and IRC. Most of the other players are Windows users. We would all be interested in the new DI tools, but sadly, if the DM decides that he wants to move in that direction, I'll have to drop from the game. If the DM and the other players decide to stay with the current setup because of me, Wizards will have lost a lot of potential customers.
You see... that's the problem here. Sure, there will be new groups that form around the DI and they will obviously form around Windows users because they won't have a choice. But there is also an audience out there of pre-made groups like mine that can't find a home on the D&D Game Table. That's a real shame because I think we all agree that the concept of the D&D Game Table is awesome... and not including users like me means that it does, in fact, affect more than just the Mac users. It affects Windows users too.
Now... here's the breakdown of value for D&D Insider (assuming $10 per month subscription)...
For DMs that use Windows, there is a great deal of value in DDI. You get Dragon and Dungeon magazine content and you get to play will all the new apps. At $10 per month, this is pretty good assuming that the apps and the content are all good.
For Players that use Windows, there is less of a great value in DDI. You get Dragon and Dungeon (which you don't use as a Player) and you get to play with the Character Creator and Character Sheet apps. So for $10 per month, it's debatable unless the Dragon content is stellar.
For DMs that use Macs/Linux, there is a decent value in DDI, You get Dragon and Dungeon magazine content which has a value of $6.50 per month ($39 per year from Paizo) and you might also gain access to some other content we don't know about yet to enhance your game. At $10 per month it could be good if all that content is worth your while.
For Players that use Macs/Linux, there is little value in DDI. You get Dragon content (you don't need Dungeon) and you don't get any use out of the apps. $10 per month for just Dragon is a bit steep. I can't imagine anyone paying for it.
So when I look at it like that, I have to say that for me, D&D Insider doesn't make sense financially. For others (DMs, especially) it will be a good deal depending on their platform. What I hope is that there will be a way to subscribe at a lower rate for just Dragon content or just Dungeon content or just the two magazines without any of the apps. This would get me to at least try it out when they switch it to a for-pay format (right now it's all free).
--sam