It's an abysmal service. You pay a pretty substantial proportion of the list price and in return you're forced to use crappy proprietary software with a poor interface and draconian restrictions on what you can actually do with the product you paid for.
To cap it all off, the subscriptions are time limited, so it's not even like you really save money. (Since you don't get to keep the book anyway, you'd do just as well financially to buy and sell secondhand.)
Edit: oh, I forgot to mention that it's far from clear in advance just how restricted the service is, and that the customer service stinks.
Last edited by random50; 06-21-2011 at 02:18 AM.