Ride them until you have a problem and then decide. Unless you have problems or are racing they are just fine. Shimano admits that they do require more maintenance than higher spoke count wheels.

I have close to 2,000 miles on mine. I am now averaging 2 mph faster than when I got my new bike that came with these wheels. I guess if I had gotten different wheels I could attribute it to that. Now I have this huge mystery as to why I am going faster!