I would be prepared with an autograph book. There were so many characters walking around and NO LINES. In fact, it was almost sad how no one seemed to care about the characters
There is an awesome doll house in one of the stores in Main Street - lots of Disney details!
Also, if you have time, watch Aristocats before your trip. I'm not sure why, but Marie is very popular in both Hong Kong and Tokyo.
Take the time to check out the merchandise. The rounded-style character items (not sure if that makes any sense), some pins, ball-shaped beanbag pillows, etc. were available in Hong Kong a couple of years before the EXACT same merchandise was available in the states. The items you see in HKDL are a good indication of what you might see in the WDW and DL in the next few years.
That being said, I went right after the park opened and things may be very different now. I have some pics in the my
Disneyland pre-trip report (link in signature).