I own the mouse, and it really has been a decent product for about 6 months; however, if given the choice between their new wireless version and the bluetooth, I'd go with the new wireless mouse (with the improved scroll wheel). The bluetooth version eats batteries for breakfast (AA's vs. AAA's, shorter life vs. very long life), and the dongle itself is only compatible with the MS mouse and keyboard. e.g. I can't connect my phone via bluetooth because of the dongle.
The special BT-enabled Intellipoint software is also only available on the CD that comes with the mouse, so if you lose the CD... well, you get the idea. To compound matters, the drivers are incredibly hard to reinstall if something goes buggy (it took me a full night of tinkering in the registry). If Microsoft announced they had plans to improve the versatility of the dongle, I'd recommend the purchase. At this moment, though, it looks like an abandoned product.
Oh, and if you just buy the mouse, you cannot buy the BT keyboard separately. Retail, at least.