I have the "chinese model" as per the e-bay link, though the labelling on the box shows it actually came from the USA.
I'm happy enough with mine. I was keen to go for the self propelled type and couldn't afford, or justify the £1000 - 1200 that branded machines seem to start from. It is a lot easier to use than standard tillers which have the engine mounted over the tines, but bear in mind that the tines all rotate the same way, unlike the branded machines which often have counter rotating tines.
This all means that if you try and dig too deep into uncultivated ground the machine tries to run away with you. The answer is to make two or three passes at increasing depths. Even doing this I managed to do most of my 9 x 33 meter plot in an afternoon without feeling totally shattered afterwards, and it does have good depth - maybe not the 18inches / 450mm that it advertised but not far short of that.
There are concerns, of course. Will it last as long as the more expensive machines - I doubt it, and don't really expect it to. Will I find engine parts if anything goes wrong, there is an address with the machine for service spares but i doubt they'll carry much more than spark plugs etc but it's certainly doing the job for me so far.
As with anything else buy the best you can afford. If £350 - £400 is your budget you have a straight choice between something like this or a much lighter duty machine from a known brand.
There is a third option, which is buying second hand, but I found very few self propelled machines around and even really tatty ones were fetching several hundred pounds.