I just got the new HP Extender through Newegg. I have been using Extenders for quite a while now. I started out with MCE2005 using the original X-Box as an extender. I then started using the 360 and, eventually, Windows Vista.
The HP extender is the first stand alone extender that I have tried and so far I like it a lot.
The unit itself is very attractive and fairly small and clean at 8.5 inches wide and deep and about 2.5 inches tall with no external antennas. The only two cables I needed to connect were the power and the included HDMI cable/ In operation it is completely silent and generates very little heat. I picked it up after several hours of use and the unit was barely warm.
The set up was extremely easy. It connected to both my D-Link 11n and my Linksys 11a networks with no fuss. It then just took a few minutes to add the extender to my media center. The process is nearly identical to setting up a 360.
Obviously, the 360's raw power means that menu animations are simply smoother. Browsing recorded TV shows, Music, and the guide, however, is pretty snappy. The only performance difference that I can see was when using the main media center menu.
The Mediasmart extender can also be used to stream content when not being used as an extender. To get it to work was easy enough. I just connected it to my wireless network and it just worked with my existing WMP11 sharing. The only thing I didn't like about this feature is that it will find all servers and display media from all active machines. In my case, I have a dedicated media center and a primary workstation. My workstation contains all my music and I maintain a synced copy of my library on the media center. When browsing music it listed every song twice since there were two servers. The solution was to simply turn off media sharing on my desktop, though I would have preferred the ability to select a specific server in the device.
At $299, shipped, it was a bit pricey but I'm glad I got it. The benefits of a silent extender with much lower power usage made it worth the price for me.