Yes, I used Delta this time last year to get myself & my dog/cat over!
Very happy with them
But, I did not fly directly into the UK, I flew into Paris with my dog & cat.
Cost much less and to be honest after reading about the process of flying pets into Heathrow, I preferred to do it that way and would do it again! Also, I would have to, as my cat is a snubnose and most airlines won't take a snubnose in cargo.
I kept my cat on board in a cat carrier & the dog traveled below. Both animals cost an additional $200 each (as excess baggage) + the cost of my flight vs. the cargo fees and the other fees involved involved going direct into the UK.
All in all, I was very happy with Delta, there was a bit of to-ing & fro-ing when I first started the process, but I made sure I got everything triple & quadruple checked with Delta and from check in, a stop-over, then an over-nite flight to Paris, it was all good

Check out the threads on this Pets board, lots of info! Good luck!