Yes, the expansions are very good. However, in the expansions, say in The Asian Dynasties, ranged infantry units such as Skirmishers, Cassadors, Longbowmen, etc., have 0.75x penalty against Cavalry units, with a 2.0x multiplier against Ranged Cavalry units - in short, 0.75 times 2.0 = 1.5x total against ranged cavalry units; this means that overall, ranged infantry are less effective in The Asian Dynasties, and Hand Cavalry are more effective. Thus, rush games are moderately balanced, but can be dominated by civilizations like the Japanese, who build shrines near huntable animals to gain extra resources (and in order for you as a non-Japanese player to then shoot those huntables, you must first destroy the shrines; they attract huntables and herdables, giving the Japanese player extra resources for each shrine, the more animals, the higher the resource trickle rate). Thus, supremacy is dominated by a few civs.
If you get both expansions, and find online gameplay hard, I suggest trying out this modification for Age of Empires III, which requires both The Warchiefs and The Asian Dynasties Expansions to play:
http://aoe3.heavengames.com/downloads/s ... ileid=3363
This uses FP1.2 supremacy balance, with added no rush and deathmatch balance, along with boosting underused units, such as Mantlets, fixing game bugs and fixing age-old problems with civilizations like the Iroquois - and also has an improved Computer AI that counters your units, upgrades their own, uses improved decks and sends cards at proper times in the game, sometimes builds walls and upgrades them, and fish booms, if possible. I, as the author of the modification, try my utmost to make the computer play like a human player - and surprisingly, I have attained it moderately. The "overpowered" civilizations have very slight changes, but more or less are the same; the underpowered civilizations, rather, are brought up into realistic playability, without threatening one civilization into becoming too powerful. Also, useless cards are addressed, such as Advanced Artillery, which in this mod researches all of your first artillery upgrades for free (Raubuld, Field Gun, Culverin Royale, Howitzers, Heavy Horse Guns), and upgrades the following Arsenal techs: Gunner's Quandrant, Trunion, and Professional Gunners. Also, cattle shipments and useless politicians are improved, as well as Industrial unit shipments and a few mercenary shipments.
If you have problems playing online, or want a decent practice against a moderately competitive AI, I completely recommend this, as you will not regret it.
If you just want an improved AI, without the mod, here is an earlier uploaded file, which I plan to update and make better in the upcoming future:
http://aoe3.heavengames.com/downloads/s ... ileid=3390
regards,
murdilator