I purchased this light about two months ago. It is indeed a nice little light. I like that is has a mode memory. The majority of my usage of this light, is in the Firefly mode. And not having to destroy one's night vision by scrolling modes is a real advantage. However, at times even the lowest mode seems a bit too bright. I have found that the old accessory cap/colored lens for the Min Maglite fit the tn12 rather well. Plus the rubber cap helps you from fumbling to find the end with the switch, as the light doesn't have a prominent projection end.
The light will roll freely when laying on a sloped surface. The Mag end also helps with this greatly.
Other little peeves include, quite a lot of beam splatter. Being in the fire service (the tn12 is NOT my primary light for this purpose), this has created some inconvenience, since I sometimes use the light in less than crystal clear atmospheres. I would like to see a tighter beam pattern.
Heat sinking is another issue. The light heats rather quickly, and while it hasn't overheated as of yet, I'd rather not subject the battery and components to the stress.
For it's price range however, the tn12 is a very nice little light and i wouldn't discourage anyone from getting one.