Well it all depends on what you want to do with it :-)
Can you use it for Media Streaming - yep - just go to the WHS Console, click settings, and follow the relevant buttons.
Can you you it as a media center - not in the same way as MCE at the moment.
If you get the right add-ins, yes, you can control home automation products.
Take a look at som of the really great websites;
www.wegotserved.co.uk
http://mswhs.com/
They will give you some good ideas as well, along with lists of add-ins and other great info.
Andrew