We've been here a month and a half now (which makes us authorities on the subject

) and overall we're very pleased with our decision to live in Happy Valley. Thought we'd share our pros and cons...
Pros:
-less crowded but still in the city
-kid friendly, strollers and people fit on the sidewalks
-easy commute (so far)
-decent neighborhood feel with restaurants, shops and cafes
-blend of lowrise and highrise buildings, lots of apartment choices
-good schools nearby
-excellent park, football fields, etc. at the racecourse
-the racecourse
Cons:
-no MTR
-prices at markets for meats, vegetables, etc are ASTRONOMICAL...sometimes three or four times what you would pay for walking 15 minutes away in Wanchai. This really peeves us...and we can't really understand it except that possibly given a relatively large expat population the merchants feel people will pay the prices for convenience. We don't -- we buy our stuff in Wanchai.
Also thanks to thewongs for a great real estate agent referral...we're now your neighbors in Ventris Place!