I've run it twice, all the way through, including some side-trecks and other mods. Not perfect, but as far as genuine "all in one, 1st to 20+" campaigns go, it's really good.
First time was with 3.5, where high level play required a lot of work to stream-line it, but the players that survived to the end loved it, a truly epic campaign, their only time running from 1st to Epic (23rd).
When 5e came out, I ran it again; we started with the pre-release alpha and beta rules, and I swapped out the first adventure, so by the time the published 5e rules came out we were somewhere around the middle of the second adventure in the AP. Anyway, yeah, converting to 5e wasn't overly difficult, no biggie compared to the rest of the prep work required especially as you got further in. That's the thing - whether it's 3.5, 4e, or 5e, at high levels you're going to have to spend time smoothing over plot holes, adjusting to your group's goals and choices, and adjusting adventures and combats etc to the capabilities of your group, more and more, as every edition doesn't scale well to high levels and pretty much always always needs ramping up difficulty to give them a credible threat and also to streamline game play so it doesn't grind to a halt once combat starts.
Similar to above, my players found the second half of AoW plot a bit weird at times, in terms of the overall flow of adventures and what the high level adventures consisted of. No real problems, just a bit weird that the only real "role-play" focused piece comes at c. 16th level, and the only real "wilderness" piece, also comes at such a high level that spells etc invalidate most of the challenge - these were great ideas, that would have been better placed earlier on. In retrospect, I could have tried to re-design the AP to fix this, however I deemed it too much work, as overall the AP plot-lines flow quite well as written. It really feels organic, not a huge rail-road, without a lot of work required as DM (my first group, in particular, felt like they had complete agency to decide everything themselves, it just happened that they chose to follow "the plot" in some way most of the time).
There's certainly some fantastic adventures in the AP, and if you look over the old Paizo boards you can find loads of help fixing some of the problems, if it's not obvious. From memory, some of the highlights are the second half of the first adventure with the Necromancer, most of the second adventure with its trio of memorable bad-guys' lairs, the lizardfolk seige in the third, returning "home" later to find it attacked by a black dragon, parts of Kyus' Zigurat were pretty epic (entrance, and final boss), and... My all time favourite was the Giant City invaded by Dragons, that was a truly Epic high level adventure that requires players to think and plan not just fight whatever moves, it played out quite differently each time I ran it. The adventures in the final City are both pretty cool too - I was worried it could be difficult to get the PC's invested in a new City locale so late in the campaign, both times it worked out well and again a great chance for interesting challenges that can't just be solved by killing everything in sight (until the final boss fight, of course, lol). For 5e, I actually added a "second boss" after Kyuss was defeated - Kyuss was actually just the Herald for the waking of the Tarrasque (which I beefed up a bit, to make it more worm-like).
Anyway, I don't know of a 1-20 AP I could recommend more for 5e - Age of Worms is great. I ran the next one, Savage Tide, using 4e rules, and we all loved that, but for me that one was perfect for 4e rules with its explicit three tiers that meshed well with the three basic phases of that AP. I read a few of the later Paizo AP's, which were not 1-20 more like 1-12 IIRC (which is not a bad thing - high level play is tough), but to me they were cool but very dungeon-centric so I really didn't find them compelling to run I felt we'd be sick of them half way through.
