I bought one of the 1140 pound ones back in 2017 to tow behind my Ford Focus for home projects. Recently helped a friend build one of the heavier ones and it was about the same building both.
The biggest advantage is their light weight. Otherwise , if you have something that has a towing capacity, I'd go with something like a carryon trailer or even make one out of an old popup camper.
The tires on mine were 65 MPH rated 4.80-12. My friend's were 5.30-12.
Bearings need to be repacked before using because the grease is just for corrosion resistance. They are metric spindles, bearings, hubs. If you plan on taking an extended trip, it wouldn't be a terrible idea to carry a spare set of bearings. The only place I found any were on Amazon. But mine made it lots of miles on the highway without a problem.
The paint is terrible. I soaked mine with fluid film and it still only made it 3 or 4 winters before getting super rusty and the paint peeled right off. If you're going to keep it outside, keep it on a tarp so the ground moisture doesn't kill the paint. And if you run it in the winter often, it is not going to like that.
As with any trailer I have / work on, I ran a separate ground circuit and tied it back into the plug. There's just too many frame sections that need to but up to each other or the lights to stay grounded for long.
Ultimately I killed mine when I loaded up over 3000 pounds of trash. The tongue bent.
I ended up buying an old 1970s popup camper, welded up some sides out of old bed frame "angle iron" and made a ramp for it. It still looks like a harbor freight trailer (legally it may still be a harbor freight trailer



) but the fully boxed 2x3 tubing frame is much more stiff. I'm still stuck with weird spindles / hubs / bearings ... made by a company called Dayton Fayette that went out of business before I was born.
If you're on a budget and need to tow smaller things or you need as light of a trailer as possible, they're worth it. Or if you need the ability to fold it's really your only option. My friends' that I helped with last year is always stowed folded up.
If they ever release the 5x10 I may consider buying that. My popup camper converted utility trailer is rusting out real bad and the axle is bent so it burns the driver's side tire off quickly. I go through one every few months now that I'm putting a lot of miles on towing my 4 wheeler.