I'm not saying you should. I have a Pogoplug that I bought for $20 on clearance and put Arch Linux on it. It works fine as a light web server for static pages and file sharing.
I'm just saying it's not exactly an original idea and the hardware is more expensive than other plug computers. The hardware only Pogoplug (i.e. before they added cloud storage) didn't seem to have great success and I'm not seeing anything in this product that is so different than the original Pogoplug concept that seems like it would be a game changer in the space.
From looking at their website for about 30 seconds, it looks like for the $50/year you also get "unlimited" cloud storage and some backup software. Might be worth it from that aspect but I haven't priced cloud storage / backup lately since all of the free offers out there cover my needs at the moment.