The price is very good. Gosh everything is so much cheaper in USA!
It is very similar to my own Chinese generic steel-framed uniwheel "Adventure C1". They are very useful for light loads. Rated to 35kg but I find low speed handling poor at anything over about 25kg because you tend to move the bike around a lot under you at low speed.. Gets better at a decent cycling pace though because the bike is kept more steady.
The premium brand / original USA made B.o.B Yak has a forward sloping headtube which helps stop your
steering affecting the
load at low speeds and allows a more carefree approach to tight turns. But BoB users crash at high speed because if the load wobbles it turns the fork and that affects the bike like a horrible speed wobble nightmare. (Try mocking it up with bits of cereal box to see)
The vertical headtube trailers like this one need to be leaned harder into low speed tight turns which is something you will learn to do after the first time it flops over when you tried to park it. But they handle high speeds better. The
load above the axle line wobbling doesn't turn the headtube and affect
steering.
Though it is supposedly a foldable trailer I think they only designed it like that so it's much cheaper to ship from China. I have never folded mine and actually replaced the upper q/r bolt with a regular nut and bolt so it is tighter and so there is more room for the box I carry in there. I would love to get it welded up with a couple of extra struts to make it stronger.
I got a bigger, beefier type of Q/R skewer with mine. I bought an extra one "M-Wave Q/R skewer" for the beater bike so I can switch bikes faster, and it looked like the one that comes with the trailer in your link, looks like it won't give as much of a secure connection with the bike, but so far I haven't bent it riding carefully with up to three 20 litre bags of compost!
I've no springs on the rear of mine. I'm not sure how much use undamped spring suspension is anyway or what load the springs are still active with. I suspect they will be fully compressed when the trailer is loaded up. Anyway wouldn't they twist, or try to twist and put an odd strain on the rear wheel etc.? You get a better aluminium fender with the (my) rigid unsprung trailer so it keeps the spray off your load and the rider behind better than this one.
I'm not sure what tyre is on that.. Hipefully a slick. Mine came with a Kenda knobby tyre which is usable but I replaced with a Schwalbe 1.75" Road Cruiser that has a lot less resistance because it is smooth even though the tyre is actually thicker, higher max pressure, but the air volume is about the same.
My trailer with no springs but lots of thick, heavy retroreflective tape all over it weighs about 18lbs / 8.5kg. I made a lightweight rolltop bag to go inside.
Single wheel is easier to avoid potholes, bumps and dog poop. But it can tip over if you don't lean the bike into tight turns. It should be used with a rear (bike) axle kick stand as in the pics there or it can be a pain to park up.
Inverted, it makes a handy table for camping. With some box steel and welding it could also be used to sit on.