Bay Ridge Blog has a great run-down of the threatened lines that affect this area of Brooklyn, and the B37 is pretty much the only route that he thinks should be kept, no questions. Here's what he has to say:
Don't Even Think of Getting Rid of the Third Avenue Bus
The B37 bus runs faster than the sluggish Fifth Avenue bus. If you take it all the way to downtown Brooklyn, you'll see that lots of people use it, especially older people who are nervous about taking the crowded subway or who have a hard time navigating the subway steps.
If this service is removed, the entire Third Avenue corridor that runs under the creaking horror that is the Gowanus Expressway will be turned into a lifeless desert. Elimination of the Third Avenue Bus cannot be considered.
The Brooklyn Paper has an article that echoes many of his (and his commenters) points. The main complaint comes from those who have trouble getting up and down the subway station steps. The 3rd Avenue bus only has two or three steps, and it's not much slower than the R train. Well, not too much slower. The Brooklyn Paper article has links to various petitions to save bus lines, but here's the link to the B37 petition.
The B37 is often ignored by those of us in Sunset Park, at least those who live closer to 5th Avenue. However, it's often faster than taking 5th Avenue (fewer double-parking issues), and it's a direct route to downtown Brooklyn, and you can avoid the crowded Park Slope stops. It's also very useful and quick for getting to Bay Ridge from Sunset.
If you so desire, add you voice to the SAVE the B37! petition. You just might thank yourself later.