Seems to me you went through the short path.
I've been playing this for a few days now, and I have to say it's a pretty fun game. However, I like the setting, and I liked S^2-3. The game is basically the same as its predecessors, but it allows you to make a few decisions here and there, that set you on the different branches of the plot. Roleplaying is not its strongest point, though. Character creation is basically restricted to face and stat selection, as you can't even play a female. Character interaction is... great for a tactical TB game, but only OK for an RPG.
The game suffers from a few imbalance issues, such as the melee skill that a mid-level scout can easily use to murder a whole platoon with his bare hands in a single turn, and the ability to toss demolition charges as if they were grenades.
Some of the skill problems of S^2-3 are still present, such as the practical inability to raise your Interrupt skill unless you want to play hide-and-seek with the enemy. This is particularly annoying as the enemy usually has nearly maxed Interrupt, and this means they constantly interrupt you while you can't interrupt them.
It has a few interesting features, such as a high degree of difficulty customization. Oddly, the "normal" difficulty is quite hard, and I had to start over as I was getting consistently raped. And I'm not a newbie to this kind of games.
The whole deal with the disguises is pretty cool too, as police officers will immediately shoot gun-toting bandits, but they will leave allied soldiers alone.
The different plot branches are a plus, too, as it's impossible to do everything in a single playthrough since some branches are mutually exclusive. Interestingly enough, you can lose the game even if you win every battle.
The only thing I miss in this game is multiplayer. The gameplay seems tailored to support it, but apparently they simply forgot about it. Hopefully they will some day release something in this engine that allows for some good ol' multiplayer carnage.