I was invited to the Windows Home Server beta program. I have been running WHS Beta 2 for about 3 weeks now. It's a great product and it really works. I have run into some minor bugs, but the product works and is feature complete.
I really like the back up feature. I admit that I do not back up regularly, but with this product I get an auto backup every night, and can restore a file fairly easily.
I also like the remote access feature. However, I think they need to add remote access capability to home versions of Windows. I think most users are going to have XP Home or Vista Home Premium in their homes and the remote access feature does not work on those systems because they do not support remote desktop connections. This would be a great value add for WHS.
I think they made storage management really easy. I do not want to fool with RAID setup. With WHS, you can add a drive as you need and if you have duplication enabled for your shares (which is enabled by default), you can guarantee that your files are on two physical drives in your server. If a drive goes down, you don't lose any data. You can also use external drives as storage.