I've ordered from them a ton, and never had any kinds of issues with them. I'm sure others have, but I've probably ordered from them probably 20 times over the past five years with no issues.
The mini ram that they've produced isn't rebuildable, but is the fastest ram available and pretty reliable. If you wanted to get the fastest possible set up, an ANS ram with a pair of QEVs is the fastest possible ram you'll get. The only problems that I've run into with jackhammers in the body threading getting stripped on two used ones that I bought. When that hasn't happened, they've worked great. They're huge compared to a lot of other ones, but they're not bad functionally and come in about every color you could want. The X5's I like and actually like in standard set ups and halfblocked quite a bit, and they have the jackal style swing frames. The quickfire sliders they made were considered some of the best frames/plates/threeway set ups you could buy. They bought the raceframe from Raceframe, and it's a decent option for electro frames. It's also the only option that you can still get multiple parts for new besides the board. I personally find most of their bodies hideous, but that's me. I love the three way I have on my twister from them.
There are a few reasons that they go for so cheap on average. They're probably the most common private label out there, and they also never started with a high price tag (they were mid-level or affordable private labels when they came out) or had an extreme milling style. That's going to put them into the lower price category of cockers once time passed. They've never been seen as the Rolls of cockers like a twister or a westwood, but they're not Yugos either. If you don't want to pay a ton for a cocker and don't like the looks of a WGP body, they aren't a bad way to go.