I guess people buy the 50mm 1.8 II for reasons of cost, Ä100,00 or so, and the quality is good for the money.
For me the 28mm focuses alot faster for biking shots and the small dof from the 1.8 is not an issue.
If you are looking to buy a lens, I suggest you think about the type of pictures you are going to take and but the appropriate lens.
Read some of the reviews here.
This place has some good reviews and a forum which seems OK.
More reviews here.
dpreview[/url] seems to have its fair share of fans.
Good luck and keep taking pictures…