Short version: Not a bad game but I'd get it only if I knew I would be playing with friends, and even then I'd wait for a sale.
Long version: Running with Rifles is all about being a little dude in a vague war that eats dudes up by the thousands. Reminescent of something like Infantry Online (although with much snappier controls) RWR pits you, and the army you belong to (out of three available choices), in battle against hundreds of AI opponents or a few dozen other dudes thrown into the mix.
Starting with the good parts, the game features relatively good controls, a handful of nicely detailed, varied and sizable maps for you to fight in, and a handful of weapons plus equipment that all have strenghts, weaknesses and important uses. Combat is frantic in general thanks to a damage system that will make every single bullet have a chance to kill you and firefights with big groups of enemies and allies on screen are exciting to watch and participate in; your soldier being able to gain experience and thus access to more equipment and options like managing other soldiers or calling for artillery/air support both a nice incentive to keep playing.
Onto the bad though... RWR biggest's failing is that it ain't great at anything it sets out to do, and actually frustrating if you are playing either online without friends or single player against bots. The crux of this issue is both in the AI and how much control you have over the battle- the first because AI is simply not reliable enough to effectively fight or go after objectives; and the latter because no matter how well you fight, you simply won't have enough to turn the tide in your favor.
You see, how many kills you get is actually not that important in RWR. What's important is having warm bodies occupying the different cap zones that let you get control of areas... and this is simply impossible for the AI to do, with alarming regularity. Infantry combat against AI is so messy, mostly thanks to a spawn system that makes soldiers pop up out of thin air in the surrounding area to the battle, that long frontlines are impossible to establish and more often than not you will be fighting enemies coming from at least 3 sides- something that on more than one occassion can hold reinforcements up indefinitely unless you go take a look and in the process risk either dying or losing your original position. This, of course, means you have to start over with your effort to attack.
Vehicle combat too is flat out terrible with AI. This is especially true before you get the ability to control some squadmates to ride shotgun with you, since combat vehicles require multiple users to operate; more often than not a driver plus a gunner. What will happen is that a lot of the time vehicles like tanks just sit back at the base, unused, and when you do take them to the battle, chances are you will be woefully ineffective as non-squad AI will refuse to ride with you and do critical stuff like man the gun. It doesn't get much better when you get AI squadmates either, since even if they DO man the positions and you CAN direct them to drive or attack certain things, their driving will be wobbly and erratic while their gunnery will pick odd targets in the general area you pointed at. It's not unusual for a tank to take a shot at a single enemy soldier when there's an enemy tank right in your face. All these problems are exacerbated when you have a vehicle crew made up of pure AI, in which case the vehicle will do things like constantly go forward and reverse, endlessly bumping against walls and other obstacles while the bots make hiiiilaaaarious quips about how the vehicle must be broken.
So, if the AI is not much use, then surely you can put on your big boy pants and get things done, right? You can git gud, as a lot of the community will tell you, and win the day, right? Well... sort of. The dirty secret of RWR is that when the playerbase tells you to get good, they are in reality telling you to go grind your face off. Experience for your soldier is paramount: It lets you do everything from using more than the standard rifle, shotgun and machinegun to wearing a bulletproof vest and commanding squaddies. Without experience, you are simply a chump with a gun and a lot of the more varied side objectives that the game pretends to have are simply out of reach. Commandering a tank and actually being able to drive and fire at the same? Not without a squaddie and couple hours under your belt, boy. Using C4 to destroy objectives, a lot of them otherwise tedious to take down or straight up undestroyable without you killing yourself thanks to the explosive radius of other weaponry? That would be 1000 xp points, please. Wanna sneak around? Not without grinding so you can use this silenced submachinegun you won't. Want to survive more than one bullet? Might as well let your medals stop it for you cause you ain't gonna get a bullet proof vest unless you go and capture like 10 bases and kill 500 guys, John Doe!
The grind in the game is just harsh. With the default settings, and that of the official multiplayer servers, it takes literally hours of gameplay for you to unlock gear that in other games would be pretty damn basic. Not only that, but in multiplayer progress is NOT shared between servers other than the official ones; so if you don't like or can't connect to those, and by the way the server browser doesn't show you server pings for some ungodly reason, you will be forced to meander about with the prospect of losing hours of progress if any server you like up and disappears. Then again, even with human players taking objectives is STILL kind of a crapshoot, so maybe you are the lucky one if you can't play.
Anything else? Yes. The game's tutorial is barebones and disjointed. Items on the ground can be hard do discern and even harder to pick up without you stopping and messing with your inventory. Weapons between factions are not nearly as varied as you might initially believe. The manual is poorly labeled ingame and actually located on the game's wiki so chances are you might miss it. Vehicle handling is sometimes oddly wobbly like you are controlling an inflatable and shooting/tossing grenades around corners or at something like rooftop enemies and objectives is fiddly, to say the least. There's also a lot of odd idiosyncrasies here and there, like the fact that your soldier will automatically rise from cover to shoot but not to throw grenades and almost every soldier has a med-pack despite them only being useful for downed people wearing bulletproof vests. Something extra to keep in mind is that a sizable portion of the game's community has a colossal boner for keeping some imaginary tacticool status quo, so not showing enough reverence for the game in forum posts or posting a negative review, like this one, will make a pack of hounds emerge from their hidey holes and either offer sarcastic advice or downvote your review into oblivion (check review usefulness scores if you don't believe me.)
For all the negatives though, RWR IS fun. There's still a long way to go for the game and pretty much 90% of the issues with it can be avoided if you play with a group of 3+ coordinated friends, since that will not only let you avoid a lot of the issues with AI but also give you the power needed to progress through the maps efficiently. The modding scene is also fairly alive, although for the moment mostly with simple soldier reskins/remodels, and the developers have promised to keep working hard on the title for at least a little bit longer so we might yet to see some improvements. As I mentioned in the introduction though, and at the moment, I consider 15 bucks per copy as a bit steep considering the limited value of the title. With some more work or maybe a sale that would put the game at 10 bucks a pop or so, RWR would be a solid recommendation.