Firstly, the Yaltec is astonishingly bright. To say it is the brightest torch I have ever seen just seems redundant: it is MANY times brighter than any I've seen, save a couple of twin handle affairs that need two handles and a strong back to manoeuvre.
It is impossible to look into the beam: the second the LED comes into view, even from a wide angle, your eyes burn and your brain screams at you to look away. Don't try it. The spot projected onto my hand from 20cm away hurts to look at for several seconds when eyes are adjusted to a moderately lit room.
The casing is sturdy and appears to be of high quality; there are O rings on all seals but I chose not the submerge the torch to test its resistance to water! I don't need to say much about size; it's small, and the dimensions are in the description.
The Yaltec has a wide fringe of even light around the central bright spot: imagine a fried egg, with a central yolk and wide white surrounding it (but substituting colour for intensity).
Batteries: the torch comes with 2 Energizer disposable CR123A batteries (around 1500mAh) which I briefly tested before switching the the rechargables I had bought. These are off brand 1000mAh 3.0V Li-ion cells which I had charged until the green light appeared on my Since SE-H001 charger (cheap, mildly alarming heat output).
I decided to do an unscientific test of battery life to get an idea of ways in which it may be useful. For this, I used the aforementioned rechargables, fresh out of the charger for their first use. For comparison, I used the next brightest LED torch I own: the Alpkit Gamma headtorch (with partially depleted batteries - told you it was unscientific). The Gamma can, at a push, be comfortably used as the front light for cycling on unlit country roads.
I pointed the Yaltec at a wall around 5m away and turned it on. I kept a running time to the nearest minute and noted down some observations over time:
* 10 minutes in and the torch didn't seem to have dimmed significantly but around the 5-10 minute mark, the temperature of the metal torch body had risen to the extent that all but the cap end were too hot to touch for more than a few seconds.
* 15 minutes in and the beam appeared to be as dim or dimmer than that of the Alpkit Gamma. However, this is comparing the central focus of the beam and ignoring the Yaltec's wider beam.
* By 20 minutes, the Yaltec was significantly dimmer than the Gamma and the temperature of the casing had fallen significantly so that the entire torch including the lense was merely warm to the touch: clearly as the battery voltage dropped, so did the heat production
* At 30 minutes, the torch was dimmer than a small, cheap, single AAA LED torch running off partially depleted batteries and at the limit of what I'd consider a useful torch. I kept the test going for another 5 minutes without any significant change, then turned off the torch, by now around room temperature.
These figures are obviously very rough benchmarks and could be affected by choice of battery (the stock ones would have lasted longer) and patterns of use - leaving it on solidly and allowing the torch to get hot could have led to reduced/increased battery performance.
In summary, it's a bright, bright product which could be very useful, but it's use is limited somewhat by its restrictive battery life.