My addition to this very useful thread. In no particular order:
Magnesium 15ga finish nailer--seems very well built, drives nails no problem.
23 ga pin nailer: works fine, no jams, although the HF pins like to change direction in the wood
18ga brad nailer/stapler combo: threw it out. jammed constantly with staples
Mag coil roofing nailer: I have only ascertained that it will, indeed, shoot nails. Bought the better one, although it cost a little more, because the "mag" finish nailer I have seems quite well built. I have a small roof project and then I'm through roofing for life.
6 in 1 framing nailer: misfired a lot then jammed, had to disassemble to get at the nail. then realized I had no freaking idea how to put it back together so I threw it out and bought a Max from Western Tool. The Max is sweet!
4.5" angle grinder: works quite well. For $20 on sale you can't beat it.
Dual 151 welder: just got this to learn how to weld. Seems ok, if perhaps a bit more finicky than a Miller or Hobart. It's on sale (if you have a coupon) for $120 off retail. Cheapest 220v welder around?
Misc welding accessories: stuff that goes on the angle grinder seems good (flap sanders, wire wheels and cups). vise-grip style welding clamps are crap. Welding cart good, but 151 doesn't fit in it very well. Argon regulator: bought one, broke it. Bought another, didn't work. 3rd one is the charm. $6.99 leather welding apron: strings are too short to tie behind my back (I wear a 33" waist, so it ain't my portly demeanor). Mig pliers: not bad, do what they need to do. Angle magnets: great, bought a bunch. Butt joint clamps: haven't used them yet, seem adequate for the intended job. ARgon bottle: my local welding company exchanged for a full tank with no questions asked, so I guess it's ok.
Solar patio lights: crap, could barely see them. Of course, here in the Pacific NW we get very little sun in the winter, so maybe they never got their batteries charged enough?
10' yellow extension cord: excellent. HD and cheap.
$3.50 ear muffs: great, like them better than my more expensive ones. Comfortable and quiet.
Dead blow hammer: very orange, but it works as advertised. Great buy even when not on sale.
Small wood carving set: pretty decent, actually, if you're ok with honing them constantly. I have nothing to compare this to, however, being a noob at wood carving.
Blue aluminum quick jack: light and works fine for cars and mowers.
I kind of subscribe to the theory someone mentioned on this thread that if you want to find out if you're going to use a tool sometimes SOMETIMES HF is the way to go. Not always. If it requires precision I'm inclined to pass. for example, if I bought their super el-cheapo sliding miter saw, I would expect it would be adequate for framing but not for trim carpentry. The welder was a perfect example: reviews say it's a good welder, not a great one, but it's CHEAP. so if I really get interested in welding, and learn on it, I'll have a better idea of what I want to buy for a 2nd welder (not HF). In the meantime, if it gets wrecked who cares? I'd rather have buyers remorse for a $5 tool than a $500 one...