Yep very good value service and you can see why it's getting a lot of praise, and why even Microsoft themselves are starting to copy it too. Though their free games are pretty fail so far.
Yes,
grab everything that is available to your interest as you can. Even if you don't have the hard drive space for it, just hit the download button so that it will be saved in your transaction history and save it for later. So as long as you are subscribed to the service, you can build up a nice "free rent of games" backlog if you will.