The Streamlight TL-3 is my most-carried light when out in the wilderness. I've got some other very nice lights in my collection - some are smaller, some are brighter and some throw even further. But the TL-3 is the best all-rounder. However, to be balanced, I'll do some pros-and-cons:
PROS:
LIGHTWEIGHT: Very light for a 3-cell flashlight that throws. Weighs exactly 200 grams with batteries and lanyard.
SMALL: It's fairly incredible to be able to put a light that throws this well into your pocket!
AFFORDABLE: WAY cheaper than anything else in it's class. Bulbs are also fairly cheap (because you only need the bulbs - there is no lamp assembly attached!)
BRIGHT: It is very bright - BUT ONLY ABOUT 170 LUMENS comes out the front! This is my observation based on other lights, plus there are other people on CPF that come to similar conclusions. Streamlight claim bulb lumens which is always more than actually makes it out of the window.
THROW: For such a "small" reflector, the throw is astonishing. Something that small shouldn't be able to throw that far (when compared to various other flashlights with their various sized reflectors) - but it just does.
SPARE BULB IN THE HEAD: This is a brilliant feature.
FLEXIBLE: You can remove the clip if you want, (using an allen key) without compromising waterproofness. If you are thinking of using it to whack people with (shocking!) then this might be a good idea - less chance of ripping your hand up with the clip! It is also flexible in that the beam can be focused - however I find this of limited use - I always keep it tightly focused, to get the most "throw."
CONS:
BULB FALLING OUT: There is the rumour (already mentioned) about problems with the bulb getting pulled out when you adjust the focus. This has never happened to me. I hardly ever adjust the focus, and if I do, it's usually just after I turn it on. I suspect that it is more likely for the bulb to get pulled out if the focus is adjusted AFTER the head has heated up, due to expanding components (i.e. the rubber ring expanding and gripping the bulb).
BULB LIFE: Streamlight themselves say that the bulbs will probably only last 3 to 5 changes of batteries (yes - worst case is that bulbs might literally only last 3 hours!!!). I suspect this is because there is no halogen in the bulbs. It may also be a conservative estimate - some people reckon they've had 7 hours. If you use it intermittently, then the total bulb life will be reduced even further, though! SO IF YOU GET ONE, STOCK UP ON BULBS!!! I've never had to replace a bulb yet - but I only use it very occasionally when navigating at night.
BEAM PROFILE ON WIDE FOCUS: This is fairly poor, despite the stippled reflector. Best to keep it on tight focus - not only does this give best throw, but the side-spill is very good even on tight focus.
[EDITED TO ADD] BUTTON IS FLUSH WITH TAILCAP: This means it might be hard to operate if you were wearing thick gloves, for example. You would probably have to rotate it for constant-on rather than press the button!
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Well, that's probably the main pros and cons that I can think of. But there is something else you should probably check out, and that is the availability of spare bulbs etc. I could be very wrong here, but I have a feeling I read somewhere that Streamlight no longer make the TL-n series... Hopefully somebody here will set the record straight. I got mine AFTER I heard the rumour, but got plenty of spare bulbs to go with it! Perhaps you should contact Streamlight to check this...