I COMPLETELY agree with Gamespot's and other reviewers sentiments that online is shallow; though, that's not to say it isn't fun (it's very fun). But as a strategy game, it is extremely shallow, particularly the skirmish mode. In fact, the game is very strategy lite overall (campaign and online). Anyone who has played a strategy game or even Advanced Wars before knows what I'm talking about. Without an economy, base building, or unit production (and control over it), the strategies that you can employ are very limited as you and your enemy will always be evenly matched and will always have the same deployment of units. Then what it all boils down to is who has the fastest shot and who can move units around the fastest--not who can strategize the best.
Here's what could have made the game infinitely deeper and what they should strive for in BWiii:
-Economy. This could be as simple as it is in Advance Wars: capturing cities to increase funds over time. Or they could take it a step further and include actual resource harvesting and whatnot. However, there needs to be at least the basic AW style economy.
-Unit production. The game needs the capability to actually produce units in the factories and such, and you need to have control over that production. So rather than just having units respawn when yours die, the game needs to give the player to produce whichever units they want, which would be tied into the economy.
-Different victory terms in skirmish mode. Rather than racking up points to a timer, the games should play out more like AW and traditional strategy games in which you have to either eliminate the enemy's force or capture their HQ. This would obviously require big maps.
Base building. The ability to use funds to build your own base (e.g., factories, barracks, etc.) would add exponentially to the game. Also, the enemy would then have the goal of destroying the other base as well. However, this isn't totally necessary. Pre-deployed buildings that can be strategically captured works fine as well.
Unit upgrades. Also tied into the economy would be unit upgrades at research facilities. Here you would not only unlock higher level units, but you would also upgrade the firepower, armor, etc. of your units. Again, this is not necessary but would add a lot of depth.