I think he’s genuine, or at least that’s what the writers wanted us to see.

But the execution is poorly done: (this is a rant)

in Dark Cybertron, Megatron doesn’t care shit about Bumblebee, there’s no way Megatron will change heart for him. But since the idea was forced by Hasbro, I don’t really blame Barber for having to somehow figured something in a short time.

In MTMTE, we saw the trail, which is more about Megatron getting away from than him actually said he regretted the things he did.

Later, while we saw his past (which was great), we never really saw him actually deal with what he has done in the presence time.

The whole DJD finale is a mess and Megatron was OOC.

He’s like “Oh no, I fuck up this game, time to press the reset button and forget about everything and look I am so tired and depressed” instead of “OK, I’m gonna fixed my mistake, tied up my loose ends, and actually do something”. While he was genuine, it feels irresponsible and cheapen the second chance he got in the functionist universe.

To think Megatron is the co-lead in a main comic title that runs his “redemption” arc for more than two years? Eh, it’s really not satisfying… even Kallus from Star Wars Rebels got a better redemption arc when he’s just a side character in a kid’s cartoon show.