We used Lending tree and got ripped off on all the additional costs which weren't disclosed until after the loan closed. We were quoted one amount for all the closing costs but on the final statement it came to over $1000 more than quoted. I would not reccommend them to anyone.

We used LendingTree once - for a quote on a re-fi - simply out of curiosity. We ended up going back to our original lender (better rate, fewer hoops) who expressed concern that our credit record showed so many inquiries - apparently, when you use LendingTree, the lenders all hit your credit report to pre-qual you. But the result is that some lenders do not look on those stats favorably.

LendingTree is a great place to start your search for a loan. They will send you a bunch of offers right away, which you can use to gauge the market rate for the loan you're looking for. It can be a pain to deal with all the different emails and calls from lenders, but it's the best way to reach out to a bunch of them quickly. You can also use them to get pre-qualified for a mortgage if you are in the market to buy a home, which can help with making an offer and figuring out the max on your price range.

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.