Spot on with every single thought/statement you made.
I received ours yesterday. Within moments I had my ladder out and was sitting on the top of our roof searching for the best location. I mounted the antenna on the end of a 10 foot PVC pipe, ran better RG59 cable inside (wasn't too keen on the thin stuff they included), hooked it all up and had the green light. I pulled out my cell phone and I was beyond excited - I had bars indoors which I've never had before. However, my excitement quickly vanished as I walked maybe 10 or 15 feet from the base and the signal was entirely gone. I didn't even have to go around a corner - I was in line of sight. Very disappointing. I moved the base to other locations in the house, and no matter where got the same result.
If you live in a small studio this is probably a wonderful product, as it does bring the signal in. However, again, as you rightly point out, for the premium price of this, I would have expected better performance. I see that they do offer additional antennas to blast the signal stronger indoors, but I'm not coughing up and gambling on another $100 to $200 possibly resolving it after I've already laid down $300.
As much as I hate to stay with the landline, until our cellphone provider provides femtocells, we're going to have to stick with what we've got.