Count me as another person who really enjoyed Mines of Phandelver. I've used various parts of it here and there, rather than run the whole thing end-to-end. It's nicely modular, a fairly gentle introduction to the new rules, great maps, feels very old-school, and the dungeons had multiple paths of exploration (rather than forcing action through one or more choke-points).
I was less disappointed in the first Dragon Queen module than some others (don't have the second one yet). I've heard accusations of railroad, which I just don't see. One thing that helped me was to see it as a collection of individual modules, rather than a single adventure. If you look at some of the locations in isolation, they're tremendously sandboxy. I was particularly impressed with the swamp location, which is as sandboxy a thing as I have seen in years. Open and extensive map with many approach points, flexible NPC locations, optional allies, time schedules, guidelines for different PC approaches (assault, infiltration, prisoners, etc). In fact, most of the chapters after the first two were pretty decent. It's kind of unfortunate that the opening couple of chapters were kind of weak, in my opinion. And by weak, I mean: horrifically lethal and off-putting for new players, and lacking in flavor, story and memorable NPCs to hook people into the new campaign.
Still, Mines of Phandelver is my favorite module so far for its elegant simplicity and neat hooks. Kudos to the authors.