The Harbor Freight model is excellent for the money. But the Garrett ProPointer is actually a better "value" in my opinion. I have both units and I vastly prefer the Garrett. The fact that it beeps faster as you get closer to the target is invaluable. Plus, it can be detuned which helps when you are dealing with larger targets. The HF model just beeps, period. The HF model also has the button in a poor position and it is easy to accidentally hit it when storing the unit in the provided holder. Finally, the HF is not known for being high quality and many people have had to replace the button. You get what you pay for so don't expect miracles for $16.
Don't get me wrong. If on a tight budget the HF model is well worth the money. And it is definitely a good buy as a spare. But the Garrett is top notch and you won't be sorry that you spent the extra money on it. I took my HF on vacation with me because I didn't want to risk having the Garrett stolen out of my luggage. It served its purpose. But I found myself missing the Garrett.
If you have a Harbor Freight store right down the street (like I do) then go ahead and buy one. What do you have to lose besides $16? After you've used it a while you will either love it or decide that you'd like something a little better. If you decide that you want to upgrade then look at the Garrett ProPointer.