Depends how hard you look. I bought a 2010/11 Chelsea home shirt from them. My brother bought the gross 2010/11 black Chelsea away shirt and this seasons Chelsea white third shirt. I've had the official versions of all these shirts so I was able to compare them...
Side by side with the real deal they do look really good, but you can see their short comings. The material isn't as nice and they're not as comfortable as the official stuff. Both my brothers shirts were pretty much spot on. The home shirt I got had a bit of a dodgy crest, the yellow stitching around it was a bit skew so it covered the bottom of the Chelsea lettering.
Few things to note. Don't get them to print names and numbers. The lettering and numbering they use is really heavy compared to the proper stuff. You can actually feel the weight of it on your back. And sizing, as far as I know they only do medium and large. But if I remember correctly, their medium is actually a large sizing and their large is extra large. So as an example, I'm fairly tall and slim 6'2", and I take a small adidas shirt, I got the medium from Soccer triads and I might as well of been wearing a tent. So I gave it to my brother who is pretty well built and it fit him fine.
All that said, to the naked eye, if you're not going over it with a magnifying glass, most people wouldn't know it was a fake.
Amen brother. That's pretty much my attitude. In fact, I think this fairly shit season has done a lot of our fans a world of good. Brought a few people back down to earth. A stint in the Europa league wouldn't kill us either...