I'm not sure if Yewen has had one, but I've had mine just about a year now and it's extremely good. They have a newer one out now, that has significantly more cooling capacity, but I'm happy enough with the older model.
In terms of setting it up, it was very straightforward assuming you buy all the bits at the same time and read the instructions thoroughly before installing. The 'all the bits at the same time' caveat is because I bought my graphics card blocks after everything else and they were a different tubing diameter. It was no biggie as they went back and I got new ones by return of post, but sometime last year, there was a change in the stock tubing size. The new stuff is bigger and therefore better apparently.
There's very little to mess up really. Depending on where you buy it from, they'll often fit the blocks and leak-test it for you. At least one supplier offered to ship me a system with the coolant pre-filled, but they didn't recommend it.