Trout/Betts is a bit exalted, let's hold off on that. I have been thinking a young Roberto Alomar, although Gleyber is hitting a lot faster than he did, but a Hall of Fame 2B is a high enough bar for now, I think.
The power this soon is surprising to everyone and he is not getting cheapies, his average HR length so far is 404, Stanton is 402 by comparison. The game-winning HR off Snell on Thursday was maybe his best AB yet, he looked bad on a few 96 FBs at the top of the zone, worked the count full, fouled off a tough curve that was in the zone, and then somehow hit another 96 at the top of the zone and off the plate outside and hooked it all the way into the left field seats, dunno how you pull a pitch like that that is outside and up and that hard, but I am not a 21 year old wunderkind.
Understandably he's getting a lot of media attention all of a sudden, I think that messed up Judge a bit last year mid-season (along with his shoulder), so we'll see how Gleyber deals with the increased demands on his time. He is looking like he will be the backup 2B at the All-Star Game behind Altuve, Lowrie doesn't need to be on anymore as he has fallen back and Treinen has been great and can be the A's rep.
Also I don't argue with defensive metrics much, but they seem to not like him so far and that seems really wrong. He definitely had a stretch of bad errors on easy plays, but he constantly makes superior plays that many other guys get nowhere near, his range in every direction is remarkable, good luck dropping much in between him and Judge these days. Javy Baez was the early defensive comp (Gleyber is also really great at tagging runners and was in the Cubs organization) but since I have seen him I can't stop thinking the aforementioned Alomar for the way he just blankets a huge area in every direction.
Also even up to the point he was called up, no one seemed quite sure what his single most superior tool was (odd for a consensus top 5 prospect), but the answer is I think his overall baseball instincts. He puts together consistently great ABs under pressure, he doesn't mind getting down 0-2 and he often seems to outthink the pitch selection, working deep counts, fouling off a range of pitches and often winning the AB. On the defensive side, there was a good example in the last day or two, fast runner on first and a tough bouncer that took him deep and away from 2B, but he still pivoted and (barely) got the force. It's only a smart play if you make it, most guys would have taken the easy out at first and most guys would have been right, but Gleyber is not most guys. The cool thing was not only did they get the force but the throw led Didi so perfectly into the runner that he also couldn't help but tag him on the way in, so out either way.
tl/dr: Every day is Gleyber Day.