I know this is an old thread, but I've been working as a buyer's agent for Redfin for about a year now, and I want to weigh in.
As an employee, I can tell you I have been looking for the "catch" since I found them and it hasn't appeared yet. This is the best company I've ever worked with - real estate or otherwise - in my 20+ year work history. They treat their customers and their employees with respect and as a result we all work extra hard to keep the ship sailing.
The money back at closing is really icing on the cake. Redfin agents are employees rather than independent contractors, so we are paid a salary with benefits and we receive a bonus at closing that is scaled depending on the rating our customer gives us. Customer service is what we are about. We are highly incentivized to give you level 10 Customer service. Anything less hurts a bit.
We typically only have one physical office for a region/state, so don't be fooled by the address on our business cards. Agents work remotely (no desk fees other realtors out there) and while we cover a broad territory, we try to match the agent to the area so that you are working with a local agent.
We also have associate agents who are independent contractors, and they are held to the same customer service standards. Those agents do nothing but show houses and they get paid per event (not commission). They are there so that you can see homes on your schedule. If you want to see 6 homes on a Saturday morning and your primary Redfin agent is booked already, they book you with one of the associates on that agent's team who then reports back to your agent. Your agent follows up and gets any necessary information you might request to make an offer.
We are able to do all of this due to the efficiency of our model and the amazing software we have backing us up. Because of the team methodology, we are able to service more customers, at a higher level. (Company model depends on volume). We don't have to prospect for clients, because they all come through the website. As a realtor, I cannot express how much I love this fact. None of us want to solicit you for business. We would much rather you come to us when you are ready. This makes that possible.
So, I would encourage you to check out the website in detail. There is a lot of information in the pulldowns beyond the home search capabilities. We don't require buyer agency agreements until you are putting an offer on a house and it is specific to the home. We wont ever pressure you to make an offer you are not ready to make. I would encourage anyone considering them to try the on for size.