I have been using 4ColorPrint (Silkcards.com) since 2013, and while the process hasn't always been seamless, I have yet to find a company that can match the products they offer for the price. I agree with other reviewers that there may be a few "toss cards" that may not be perfect because of packaging during shipping, but considering they're coming from overseas -- it should be expected.
I am a graphic designer with 20+ years in the industry, so in my experience as long as you are providing the correct files, they'll print just what you expect of them!!!
I've printed everything from plastic cards, silk cards, 3-layer business cards, flyers with scratch-proof finishes, waterproof cards. The list goes on! I've never had to send anything back. Everything is always beautiful.
Recently, I noticed that the communication has improved and so while I'm sure the company has experienced some growing pains over the years, positive changes are always happening. I will continue to choose Silkcards for my specialty printing needs!