I don't think it is a bad idea to travel to China during the Chinese Spring Festival, it is not as crowded as the Chinese National day and May Holiday in the tourist attractions, because most of the people will stay with their families.
The advantages are:
[ol][*]Lesser people in tourists attractions than those days during other time.
[*]Great time to see locals, more crowds on streets or villages if you want to see people.
[*]You will be able to see more authentic celebrations such as Dragon Dancing, Lion Dancing, NiuYangge (traditional dance in northern China) and other celebration.[/ol]
Disadvantages:
[ol][*]Too crowded if you want to travel on public transportations such as train, long distance buses. Flight will not be too crowded becouse majorities are still using trains.
[*]Cold in Northern China.[/ol]
Suggestions:
[ol][*]Try to avoid Trains, buses, use private car or bus as means of transportation in cities.
[*]Make flight and hotle reservation before hand.
[*]Try to see some villages or even families and to celebrate with the locals, great fun and experience.[/ol]
Victor