First off I hate sewing this fabric. It is challenging to sew. Its so damn slippery and thin. Be prepared to pin this every 6 inches or so. Thats not really a fault of the product, just the nature of ultralight waterproof fabrics.
The only flaw I saw was there was some fine cardboard dust or some other contaminant embedded in the waterproof coating. Its hardly noteworthy and you have to really look at it to notice.
This stuff is pretty tough for its weight. I used it to make a bivvy. I like the end product, but sewing this was borderline torture
2nds Quality - MEMBRANE silpoly