I really, really want to like Fellowship. I love the pitch a whole lot: it's a high fantasy game for any kind of fantasy! Players have ultimate control over the world! The GM also has a character so they can get the serotonin hit of filling out a character sheet too! But I've played Fellowship a lot now. I've been in three games with false starts (one of them I GM'd) and one game that got past the first session that got to the end of gaining Fellowship with a community, and most of the time I enjoyed with those games, I wasn't engaging with its systems at all.
First of all: this is a game that, in all the times I've played it, is a resource management dungeon-crawling game, first and foremost. It has better capabilities for roleplaying and worldbuilding than a game like Dungeons & Dragons, but it still leaves a lot to be desired on that front. My main group is extremely into inter-character melodrama, and if there are any lulls in the action we will spend hours talking to each other in-character. Not a lot of systems explicitly support this, but Fellowship explicitly discourages this with its "rest" systems; taking any time to do scenes not directly related to dungeon-crawling makes the next encounters more difficult for really no reason. I wouldn't mind this so much if I was playing a very crunchy numbers game, but when I want to tell a character-driven story, Fellowship is more or less incapable of delivering an experience I want.
Another thing related to the game's inflexibility: the playbooks and worldbuilding associated with them. Fellowship's main selling point is that you get to decide what your fantasy culture looks like, with a lot of flexibility. In play, however, I found this flexibility was a lot less open than I would have liked. If you're playing the Elf, you're more or less locked into playing a holier-than-thou character who can commune with nature. If you have a different idea for an elf, you're going to be fighting the system a lot to put together the moves for your vision. Once, I tried to use the Orc playbook to make a character whose people were known for their ingenuity, even when that, in the past, meant giving up their humanity and bonding with parasitic fungus; after taking just my two starting moves, however, I ran out of playbook moves that fit my vision.
This is already getting long and I haven't touched on my frustrations with the moment-to-moment gameplay, or the frustrations the GMs of my groups have run into. Let me touch on the former (where it doesn't relate to the latter) briefly: advantage was not adequately explained in the original edition, and putting it entirely in an appendix for the revised edition is less than ideal; I already mentioned before that decompressing after long action sequences is basically impossible. The latter is a huge problem that bleeds over into the moment-to-moment gameplay, and most of it boils down to two things.
First, giving the GM a playbook makes them rather precious over their Overlord and General characters and fosters a hostile relationship between the players and the GM. In my experience, since the GM knows their villains are finite, they scramble to find reasons why the PCs can't kill them right now, and often resort to underhanded tactics. All the GMs I've played with have said they felt incentivized to give threats secret stats that negated certain attacks, creating an atmosphere where players were too nervous about wasting any moves in case they activated the GM's trap cards. Second, though the second edition is a marginal improvement, there's a notable dearth of information on how to be a good Overlord. The newer GMs struggled to find a footing or guidance in the GM's sections at all, and more veteran GMs were frustrated by lack of guidance for creating tailor-made threats/setpieces for whatever unique world the players created.
If you're really desperate to play a PBTA version of D&D, I recommend Fellowship over Dungeon World as it's slightly more flexible. But, honestly, I'd give both a pass. It's a shame and I miss playing high-fantasy adventure games at my table, but Fellowship doesn't scratch the itch for me at all.