I buy from Japan constantly, both Ebay, Yahoo!Japan Auctions, and Japanese stores. I think in the 15+ years I've been doing so, I've had two? problems, one of which was an easily resolved shipping issue (USPS misrouted the package, said it was undeliverable, and sent it back) and one never received item from Ebay, which may have been a lost package as well.
It's never perfect, but I've not had anymore problems than anywhere else.