I try to only buy stuff from Harbor Freight if I know it's a tool that won't get much usage and won't get me killed if it breaks. I've had some bad luck and some good luck with their stuff.
Good:
Silver and blue aluminum jack: It's built to a price, but I've had mine for probably 7 years and it still works great. There's a little slop in the jacking mechanism, but it still pumps up fine and holds well. I've even dropped a car on it and it still keeps on working. Good buy. Just be aware that it's not exactly designed for use on tall trucks.
1/2" torque wrench: Great tool! I was ||this close to buying a $300 "nice" wrench, but figured that I wouldn't use it often enough to justify the expense. Pretty sure I only paid $10 for this on sale and it worked perfectly for reassembling and torquing everything on my Camaro engine. I even went to the trouble to check the calibration on it multiple times and it was bang-on every time. Very, very good deal on this wrench.
Low profile creeper: I use this all the time and have never had a problem with it. It's nice and low, comfy, and has pockets for holding tools and nuts/bolts. Think I paid $20 for this on sale. I'd buy this again and would recommend it. I'm about 180 lbs. If you're substantially heavier you might want to avoid this and buy a metal frame creeper instead.
Digital multimeter: Works great and never had a problem with it. Considering the price (you can usually get this free with coupon), it's a hell of a bargain.
Fair:
3" cut-off wheel: I think I paid $10 for this a couple years ago. Bought it to cut down some u-bolts on my Camaro's rear end. Works well enough for $10 and is still working to this day. I used it last weekend to cut my bed supports for longer shackles. Not a bad tool, and definitely worth what I paid, but it's an air hog. My 33 gallon compressor has to run non stop to keep it supplied with air. It's just really inefficient. Had I known I'd get as much use out of it as I have, I'd have bought something nicer.
1000 lb engine stand: I used this when rebuilding the 350 for my Camaro. It works well enough as a stand, but because it doesn't use bearings, rotating the engine is a real bear (not bad with a shortblock, but once you put the heads on...it's a pain). I also never really felt that it was all that strong. 1000 lb rating or not, it didn't seem built to last and doesn't like to roll once it's loaded. Not too expensive and it'll work, but if you're going to use it more than once I'd suggest ponying up for something stronger, with better wheels, and with bearings so you can actually rotate the engine without giving yourself a hernia.
Avoid:
Pitman arm puller: Bought this because I *needed* one and Schuck's was out of rentals. It's a piece of crap. I can actually see it bend during use. But, having said that, it hasn't broken yet and I've pulled two pitman arms and at least a half dozen tie rod ends with it. I'd gladly pay 4X the price for a stronger tool and would recommend staying away from this one.
Air chisel set: Stay away from these. I tried using them to get off the rivets when installing lowering hangers. ended up grinding the chisel bit to a nub, and the ripper bit dulled very quickly. Spend a little more and get a set of GOOD, hardened bits that will last.
249 piece rotary tool bit set: I would not recommend this. The cut off wheels are flimsy and fragile, the brass brushes fly apart (90% of the bristles were gone within a matter of a few minutes use), and it is just generally of bad quality. Unless you're doing a very small project, you'll use up the bits before you finish and will have to make a second trip.
Small blast cabinet: It's pretty hard to mess up a blast cabinet, but I am pretty unhappy with this one. The light is terrible. The way the cabinet opens on the side causes all the media to spill out when you open it. It's not vented properly, so media tends to blow out in places where you don't want it to. And the nozzle that it comes with is complete junk. Spraying walnut shells constantly clogs the thing, and the feed tube is poorly engineered. The bigger cabinets look like they might be better, but this one is junk.
I personally tend to avoid anything with an electric motor and air tools. Also, anything that is a high wear item (I learned the hard way with the chisel bits) or needs high precision (tap and dies and such). I'll buy consumables like sandpaper and wire wheels there, but there are still a few things I avoid (dremel bits, some wire/brass wheels).