At its best, Red Faction: Guerrilla is an absolute (and literal) riot to play.
And so on and so forth. It's this type of emergent gameplay that causes me to rank Red Faction: Guerrilla up there with some of the best combat FPSes: Far Cry & Jedi Outcast, to name two which had incredibly varied and enjoyable combat.
Some incredible weapons help with this: the singularity bomb, the Eraser-esque x-ray-scoped wall-piercing nail gun, the massive thermobaric rockets, the jetpack.
So, on the basis of combat alone, I would recommend the game. And at what... $5-$10? It's a great bargain.
The graphics still hold up. Though the environments could have had a bit more flavor for my taste, they definitely feel industrialized Martian, complete with red dust, pipes, and smokestacks. During some of the larger battles / destruction, there is a frame-rate drop BUT the game "blurs" the screen a bit at these times. This actually gives the destruction an almost action-movie, dramatic flair. Don't get me wrong, it's regrettable. But the way the developers handled it is great design.
The story is mediocre at best. Though the game is free-form/sandbox like GTA, there's no real story to the individual "guerrilla actions." Rather it's like, "Oh here are some hostages, go save them." While these certainly do get a bit repetitive, they ARE mostly optional and, due to the enjoyable combat, never dull. The main story is standard FPS action fluff - be a rebel, fight the empire, etc. About what I expected.
There are some annoyances:
*The enemy is extremely aggressive. Especially when you first enter a new sector (there are 6 which you must liberate by destroying enemy buildings and completing main missions & guerrilla actions), the enemy will absolutely SWARM you. Which makes sense, since this is Red Faction: GUERRILLA - you're supposed to perform sneak attacks, hit & runs, y'know terrorism. However, the game really doesn't emphasize this style of play enough. As such, I constantly found myself getting a bit frustrated that they sent a freaking hundred soldiers just because I smacked a sign with my sledge-hammer. Remember that: think like a guerrilla!
*The vehicle handling is a bit ehhhh. It's not terrible but in the timed vehicle sections, it can really get aggravating. Cars flip too easily, handling feels alternatively sluggish or overly responsive. Controller-through-screen frustration is never a good thing.
*Way too much emphasis on returning to the red faction outposts. You return special vehicles & hostages there. You often need to return to one to set your alert level back to green. That's where (along with some scattered caches) that you can resupply your ammo. Eventually you can get the ability to instantly teleport to them, but even then I had to CONSTANTLY travel to and from them. Design should have been better there.
And there were a few other nit-picks but they were small enough that I can't really remember them.
So, to summarize, a great bargain. If you're a fan of FPSes and especially sandbox FPS, there's no question that you should try this game out.