Having read the universally scathing Amazon reviews of the other planetarium projectors, I tried this one on the shaky grounds that at least nothing bad had yet been written about it. So to redress that balance, here's something bad:
First off, it does try harder than the others as it's both a star projector and a simple orrery, a model of planets rotating in the solar system. As could be seen from the box, it quite reasonably doesn't carry the moons that a better orrery would have. However a basic feature of an orrery is that it should show the inner planets rotating faster than the outer planets. This one doesn't - they all rotate together. Despite the great big box of plastic, there's no gearing in there and you might as well paint the planets onto a flat disk and rotate that.
The star projector is about as bad as the others and looks as if it was designed in the 1970s. It's a clear plastic hemisphere with stars printed in black, illuminated by a torch bulb. That's just not good enough. If it was simply replaced with a black dome and drilled holes, with a bright point-source LED inside, it could give a far better projection image. This is 2010 - LEDs are cheap, commonplace and I can buy a mobile phone for the price of this toy. There's just no excuse to still use torch bulbs.
On the whole, this thing is worthless. Now will someone please make a decent one? I have 50 quid to spend.
Minor points are that (positive) it has a 5V power supply socket, so that a spare phone charge etc. can be used instead of the 4× C cell batteries. On the negative side, the motor is noisy.