In all honesty they are just starting to break through in Europe, so I haven't seen that much of them. The Asian player that has impressed me most is Inamoto, his performances in the World Cup were outstanding, easily Japan's best player during the tournament. But I don't think we saw Nakata (midfielder not full-back - is it Hidetoshi? full-back is Shinji (who impressed me a lot as well)) at his best. Now that I've seen him playing for Fulham a couple of times, mostly as a substitute, he's continued to impress. If I were his manager I'd most likely start him.
With the World Cup recently being held in Japan-Korea, as long as football is nurtured in the right way in those coutries we could see a large amount of good-great players coming from this region within the next decade. This is as long as the respectives FA's keep promoting the game in the correct manner and offering good training to promising talent. Otherwise the momentum that would have been gained in those countries because of the World Cup, especially as both nations had good runs, will be lost and nothing would have been gained.
Having said that it seems that this has been done recently, it's obvious that a lot of talent coming from Japan now coincides with the emergence of the J-League about 10yrs ago, therefore the kids who were 8 years old at the time, are now 18yrs old and have been nurtured well. We may see many more in 10yrs time, due to the World Cup.