It depends actually. The video quality and sound quality, for the most part, are exactly the same as the licenced North American versions. Most Anime DVDs here in Hong Kong are not actually copies, but published by proper companies.
Due to some "irregularities" in the law, the companies which publish these DVDs don't necessarily pay licensing fees to the original anime studio. This is legal here in Hong Kong and TaiWan. It's hard to classify whether or not this is piracy though.
Most of the recent releases do have decent subs. A lot of the earlier ones (which came out on VCD) were terrible.
I'm not too worried as I understand 90% of the Japanese anyway.