*EDIT* The realtor finally got ahold of them, and apparently the person assigned to our case was out. They said they would fix the sewer, whether we purchase or someone else does. *END EDIT*
After reading reviews we were hesitant to try purchasing through Offerpad, but we decided to give it a try. They responded to our initial offer right away, but when a sewer inspection revealed major issues (basically the piping had to be entirely replaced) they said "We will gather bids and get back to you as soon as possible."
Well we waited the 5 business days required on the contract, and they never deigned to get back to us. A huge waste of time and effort. Beware of purchasing in North Phoenix - it wouldn't surprise me if they try to sell it without fixing the issue.