Clean graphics & decent voice acting are accompanied by weak AI. Play sessions ideal for portable format. Multiplayer!
Field Commander can be viewed as the PSP's answer to the GameBoy Advance's excellent Advance Wars. From a game design perspective, the two titles are nearly identical. At a glance, the most obvious distictions between the two is Field Commander's 3D game engine and more realistic art style. Dig deeper into both games, and you'll start to discern the important differences between the two titles.
Let me get this out of the way: I think Advance Wars is the better game, at least for single player. The AI in Advance Wars is better at planning ahead and taking advantage of weak points. Latter levels in Field Commander are a challenge primarily due to the overwhelming odds. There have been a number of maps where the only challenge has been surviving an initial assault, and then the rest of the level consists of steadily wiping out the enemy units. On many of these maps, the enemy also has a clear economic advantage - the AI doesn't utilize the various units effeciently. This was most apparent on a water map: I had one heavily damaged unit obstructing a choke point. The AI had a number of top-condition ships nearby yet chose to repeatedly attack my crippled ship with its own heavily damaged unit. Round after round, the two ships ineffectively fired on one another. Looking at the big picture, the AI should have pulled its weakened ship away and attacked with a healthy one.
The story of Field Commander doesn't flow as well as Advance Wars's story. There are a few places where you can choose from a few different battlefields. Unfortunately, this causes some story elements to play out of order. It was initially confusing as the out-of-order mission briefings told me to "destroy the secret weapon", then "learn more about the secret weapon", and finally "investigate rumors about a new secret weapon".
These shortcomings are mitigated my the multiplayer, however. Playing against a skilled opponent can be a wonderfully nail-biting experience.
Field Commander's play sessions are ideal for the portable format. The turn-based structure allows you to either play just a few moves or complete a few rounds, your choice. The graphics are clean and units are easily discernable on the PSP's screen.
Keeping in mind that I've become a videogame cheapskate, I'm glad I picked up Field Commander on sale. $40 feels a little steep for the gaming experience it has provided, but not by much. On my subjective experience/dollar scale, Field Commander is second behind Lumines for PSP games. (Other games include Namco Museum Battle Collection, Brotherhood of the Blade, Darkstalkers, and Wipeout Pure.)