OK, I have used LendingTree four times over the years with mixed results. The rates are ok - usually a bit better than the national average. I test LendingTree rates against the Bankrate average rates - and usually LendingTree is competitive.
BUT, LendingTree promises "up to four offers" and usually I have gotten one or two offers, not the four I was expecting. The two offers are followed by a phone and email barrage from the lenders and LendingTree. If you can pit the loan officers against eachother, you can(!) get them to reduce their rates even further. So the competition is real in that sense.
The form is long and tedious. It actually feels extremely old especially when you fill out other forms on the internet that are my dynamic and interactive. All told, the experience will take you 15 minutes or so to fill out the form and receive lender offers. Calls from Loan officers happen a few hours after that. Then, you are off to the races.