This really interested me so I decided to review their white paper which may be found here.
The biggest limitation I can note is Hydrominer plans on using GPUs for mining. For ethhash, this is fine but what about when other algorithm become more profitable that are dominated by ASICs. Hydrominer would not be able to compete.
I think the concept is great overall but think it would serve them to have a stated plan for diversity of mining equipment so they are able to better adapt to changes in difficulty among the various algorithms available. From what I understand, ethhash is ASIC resistant but don't see any reason why they can fill one of those shipping containers full of ASICs to mine X11 and Script as well.