Here are my thoughts on the new Legacy Armada Megatron (compared to the original)
Robot Mode

He is a massive improvement over the original figure. While he does lack gimmicks like the hidden blade in his left hand, and his firing missile (which hasn't been a thing with Transformers toys in the CHUG toyline since Combiner Wars, which ironically makes another Armada Megatron one of the last figures to feature said gimmick), he makes it up with improved articulation (neck, hands, heels and most importanly, knees!). Sadly (and expected) he does not come with Leader-1, and he doesn't have any ports for the minicon figure to rest, although you can still use the Siege/Earthrise Micromasters if you want. Like with the rest of the Armada Legacy toys, his minicon activated power is manual now, meaning you don't need a minicon to activate his double missile launcher. Seeing as the focus is on the figure and not the gimmicks, he also doesn't include those minicon rooms on his legs.
The transformation is a little bit more complex this time around. One difference is that his face plate is NOT slideable, but rather folds into his chest. Since he doesn't have any electronics, whenever you transform him, you don't have to hear the "DECEPTICONS ATTACK!" sound all the time.
While I forgot to take a photo, he is still able to do his Full Blast Mode, as this is what is advertised as his Evo-Fusion ability.
Vehicle Mode

Honestly I was blown away by his Tank mode. It's so faithful to the original, that I wouldn't of known it was the Legacy toy until I saw the 2 together. Granted there are some noticeable differences (for example lack of Minicon ports on the Legacy toy, and some paint), but it does a really good job of recreating the iconic H-Tank mode.
Verdict

Overall this is a fantastic update of the Armada character. Where it lacks in gimmicks, it makes up with articulation. The fact that at times I had to check twice to make sure he wasn't the original means if you want an Armada Megatron figure for your collection, I recommend picking him up. Hopefully they'll do the Armada Minicons soon, even if they are just micromasters.
I'll update this when I'm needing help finding particular figures