This is an interesting piece of kit given all the contents for the price. The adapter rings alone would cost nearly this amount if purchased separately. The mains adapter (at 3.3V) is a useful extra included in the kit and will certainly be used by me in the studio setting.
I already own a ring flash, but wanted to use a constant light as finding and focusing on small insects in shadowy places can be tricky, especially with an extreme close-up macro setup of around 3 to 5x magnification. The problem is that 2 AA rechargable batteries are just not up to the job (at 2.5V), it really does need 2 AA high power batteries (at 3V) to deliver the grunt required for all the LEDs in the ring. I jury rigged up 3 rechargable AA batteries (at 3.25V) and this worked fine, giving similar output to the mains adapter.
From my testing, I still think I am losing around 2 stops of light over the ring flash that I own, so it is my opinion that it will have limited use for macro work, but as I said at the beginning of this review, it will find some uses in the studio.
To summarsie: Thus I cannot really recommend it for the extreme macro photography that I do as the kit stands, but think it is still a useful tool in a photographers' armoury of kit. Hence the 4 stars given. Perhaps the kit would be better if it was modifed to fit 3 AA rechargable batteries instead.