What is missing here?

The amplifier has no "failings". It is exactly what it purports to be and will work well as intended. There were no "omissions". The power output was listed in the specifications. Have we gotten so mentally lazy that we need to be told that we can't play an LP in a CD player?

The amplifier may not have failings in doing what it was designed to do, within its very very limited parameters. That’s not the point here, what is the point is that the reviewer never brought up the limitations that are inherent with a design like this. I think these limitations are severe enough to disqualify this amp from most people’s ability to utilize them successfully. Since there seems to be some disbelief that folks would buy this amp without already knowing its short comings, let me relate a story that happened recently to a very sophisticated and experienced audiophile friend of mine...This gentleman goes shopping for a new amp for his fairly inefficient speakers from the same dealer that he had acquired the speakers from. The dealer sells him a low powered amp that ‘should’ work with his speakers and in his room. My friend believes that this tube amp should work, as it had a very favorable review in an audiophile magazine with good crede. Unfortunately, after about a month of trying to get the amp to work well in his system, he came to the realization that the amp in question was simply unable to properly drive his speakers, resulting in not only a ton of frustration, but ultimately a significant loss when he came to sell the amp!
Now, IMHO if the dealer or the reviewer had mentioned the fact that this amp has severe limitation in its ability to drive less than ultra efficient speakers, do we all think that my friend would have made this mistake?
BTW, I’m not saying an Air Tight dealer would lead a buyer on in this regard with reference to this particular amp, but again, the reviewer said nothing about the amps severe limitations ( ok,different from failings). An omission that I believe was significant and unfortunate.

But daveyf, now you have a grievance with the amplifier's designer too? It seems like you're arguing for hand holding for a potentially uninformed consumer. While I agree it may be nice if such education is readily provided by reviewers and HiFi mags in general, I don't feel a reviewer is being negligent if they don't caution the naive buyer on this sort of consideration. You obviously know better. Who do you imagine is the consumer who'd get suckered here? It seems to me the onus is on the buyer, especially with a high dollar niche product such as this. With so much to learn in the world of HiFi, wouldn't it be really dumb and irresponsible to throw that kind of money around without knowing what you're doing or being savvy enough to get  proper guidance (and not necessarily from a review in a mag)? I think reviewers have other objectives.

The buyer of expensive gear should be somewhat educated on the product, not relying on a review, and use due diligence. I cannot find the Absolute Sound review on line, so if anyone can paste it here, I would like to read it. Maybe I might feel some of what davey is talking about, but not likely.

@daj  Please point to where I have stated I have a grievance with the amps designer! Not the case at all. 
@mrdecibel Unfortunately, what a lot of folks rely on to get their education on an audio product is a review of said product in a well recognized audio magazine. Whether this is a smart thing to do or not is debatable, but I think most of us can agree that a lot of hobbyists give a great deal of creed to a rave review. As such, i think the omission I have been discussing is pertinent and problematical. YMMV.