The phrases are all in Japanese, but it definitely sounds just like Megatron! They are also the same as the Galvatron G1 Reissue figure, and include the following:
"Wa-ha-ha-ha, kono orokamono-me!" (Bwah ha ha ha! You fools!), "Eei, Cybertron wo hineri-tsubuse!" (Hrr--crush the Autobots!), "Kono yaku-tatazu mono ga!" (You're all useless!), "Eei, hakai shite kureru wa!" (Grrah, I'll destroy you!), and "Destron gundan, transform!" (Decepticon army, transform!)
If you would like to get a better idea of what this cannon attaches to please check out this video review article. The cannon is only one of many pieces that comes with this stunning figure. In that same article there is a gallery of MP-36 Megatron wearing his accessories in different poses so you can see what he looks like out of the packaging. On a side note the cannon will be powered by 2 LR44 batteries.