Mine has served me well. It's mostly stock, I painted all the frame bits black before I assembled it, I cleaned the Chinese grease out of the wheel bearings and repacked with Lucas, I mounted the license on a hinge, and put some turnbuckle hold downs on the sides to hold it together while folded. I upgraded the casters to larger, heavier duty ones for ease of rolling it around when folded too. I broke one of the stock plastic casters early on, they sucked anyway, they'd lock up on the smallest of pebbles, let alone try to roll over an extension cord or expansion joint in the concrete.
I shopped around for larger wheels and better tires to replace the 12" Chinese bias-plys that it comes with. I eventually found some 13" wheels and set of cheap passenger car tires that I think will fit, but have not done anything about it. I bought a pre-mounted tire/wheel combo from HF for a spare, when I bought the trailer, it lives with a 4-way in the back trunk of the car I tow the trailer around with. I may re-evaluate when the time comes, the tires are about 5 years old now, don't have a ton of miles on them though, and I can't really justify replacing them yet.
If you want to fold it up, don't use carriage bolts, or anything with a head that protrudes through the deck. I ordered some tapered socket head bolts from McMaster only after I realized the heads of the carriage bolts I used initially interfered with one another while folded.
Directions call for 3/4" plywood, but if I had it to do again, I'd buy 5/8", the 3/4" is just a little too thick to allow the two halves to fold flush with one another.
As for the bolts to hold the back half in place during use, I just run a carriage bolt through the hole from the back side, the hole is square, so it keeps the carriage bolt from spinning, and I zip a nut and washer on the carriage bolt with the electric impact, or ratchet wrench, doesn't take long.
My biggest complaint is that it's bouncy, and unless I've got something loaded on it, I can't see the dang thing. I call myself fairly skilled at backing a trailer, but this little thing has had me questioning my ability a time or two.
Frame folded up before decking was added:
When the deck was new and one piece:
Hauling stuff: