Having had the chance to play The Asian Dynasties, I find that the Banner Armies system for the Chinese is more of an inconvenience, rather than an advantage that allows you to mass units and overwhelm your enemy. In large skirmishes with Hard AI opponents (I never play online) whose armies are roughly the same size as mine, I find that Chinese armies are just as good as their European (or native American, or other Asian) counterparts; UNLESS my enemy's army is mostly cavalry (I find that the Chinese aren't too good against cavalry, even the banner army that's designed with anti-cavalry in mind fares poorly against them)
Of course, looking through my shipment deck, I find that there are a LOT of unit upgrade cards, so perhaps that explains why my Chinese army can take on enemy armies of the same size (could be possible, but I doubt it)
And now, onto the artillery. Unlike infantry and cavalry units, you can train the Flamethrower and Hand Mortar units individually, although there are banner army options which include them. 5 flamethrowers do wonders against infantry, and can knock down a good number of buildings. Hand mortars, while you'll need a group of about 10, can wreak havoc on enemy artillery (thus sparing your infantry from being massacred), and with their long range capabilities, can take down buildings with ease. Flying Crows, while they are deadly, are not my favourite artillery unit, as they move slowly, take too much time to unpack for battle (similar to how trebuchets in AoE2 need to unpack), and you can't train them, you can only get them through home city shipments, or an age-up wonder which produces them very slowly.
As for the Chinese single-player story campaign, which deals with the 1421 hypothesis, I was disappointed with it. The only natives they deal with are the Aztecs, and after the campaign, the Chinese 'clear the beaches of any sign of their presence' and set sail to go home. Also, while the storyline involves a treasure fleet, there is no mention of Zheng He, or any historical figure, as opposed to the storylines in the original game and in the Warchiefs, where the main characters meet people like Washington or Bolivar. Oh, and while the story is set in 1421, the flag of the Qing Dynasty flies over all of your buildings