I had no issues using them last year. As a matter of fact there was a whole subindustry of churning your mortgage as interest rates kept falling. Better.com allowed for that because of how seamless everything is and they would price match any rate you got.
Of course if you have some edge case and tons of questions or issues YMMV and you'd have similiar back and forth. Their call center which seemed to be staffed in the US was always helpful in answering questions or escalating if there are delays in the advisor side.