I think this solution is quite interesting and probably fits their needs but comparing it to the storage solutions of the vendors listed is quite ridiculous. Another thing to note, there are vendors, NEXSAN, that sell cheaper storage systems, that while still more expensive then this, would have probably meet their needs.
The first issue is high availability. There are many single points of failure on this box. There is only a single controller. The power supplies are not redundant. With the number of drives a single fan failure might lead to and high enough heat to damage components. Single port back plane. No NVRAM. The only thing that isn't a single point of failure are the drives themselves because they are in a RAID6 config but I still see a problem with that, their configuration uses no hot spares.
A high end storage system is going to have multiple controllers, redundant power supplies, be able to sustain multiple fan failures, multiple back planes with interposer cards. It's also going to have NVRAM that should a power failure occur acknowledge cached data would not be lost.
The second issue is maintenance. A high end storage system systems parts are high accessible and often hot swappable. A controller goes out, it's like changing a Nintendo cartridge. With this box if anything goes except a drive, the box is coming down. If you are a replacing a drive you'll have to slide the box out, hopefully you left enough clearance for the power cords when you slide it out, then you have to pop in a new drive, and hopefully not break the SATA connector on the back plane. Oh man, I forgot to put on a new rubber band, I mean vibration dampner.
What's the performance of this box like? With software RAID and only a single processor with no ASIC acceleration for anything I would have to imagine the processor is going to get pretty bogged down. With a high end box everything is pretty much designed, within reason, to make the drives the ultimate performance bottleneck. Can this systems fully utilize all the drives or can the drives deliver more IOPS and throughput then the controller can handle?
Extra features. What does this box offer in terms of volume copying, flash copying, and remote mirroring? The value of an enterprise solution is that it provides the features that keep it working 99.999% of the time, not just 99%. I see so many possible areas where data could possibly be lost or corrupted.
A couple of comments have suggested this just being a block in a bigger solution, treating it just like a drive. In that case you are going to have to a additional layer of redundancy, probably a mirror. With a straight mirror you are going to see a doubling in cost of hardware, infrastructure, power and cooling, which is going to start disrupting cost/benefit of this solution.
If you just want a bunch of file space accessible through HTTP with the ability to tolerate the occasional loss of data and downtime, this solution will work fine. If data loss or downtime means the loss of data or jobs, you'll go with one of the major storage vendors.