I think the important thing for a homebuyer, especially a first-timer, is to get the best agent they can, regardless of whether they get a rebate.
Home shopping is different than looking for rentals, where "this'll be fine" is just good enough.
A buyer's agent should know enough about homes to help you find one that fits your lifestyle, help you evaluate the home for livability (not just, here's a bedroom), help you anticipate the quality of the finishes and their place in their life cycle (nice kitchen, but the finishes are pretty cheap for such an expensive house), help you anticipate potential maintenance and repair problems (shake roof vs composition, wood gutters vs vinyl), and the potential for remodeling and improvements (is there a ready place for a stairway if you wanted to build up, for example).
On top of what you would presume are the basics, which is to open the door for you and write up the paperwork.
Oh, and to make sure you're not missing out on a better house than the one you decide on.
I'm sure I could think of more things, but I'll leave that to my colleagues.
All the best,