I'm sorry buddy. But you're a fish. You bought a game because a best buy rep told you to buy it? If anything you should be mad at yourself for being so gullible and for being unable to make educated decisions by yourself.
If you were smart, and you were me, you would tell the guy: Maybe next time.
Then, you would go back home, go on the internet and actually READ the reviews about the game. If you would have done that, you would have known exactly how the game plays and exactly what it lacks. That's what i did and the game ended up being exactly as i expected because I read the reviews and thus, knew what to expect. I also knew to expect LONG games(Gamespot, for example, states in the "bad" that you will probably lose sleep over it) and to expect a LACK of a campaign mode. Personally the long games factor was a selling point for me because, although i LOVE Strategy games, traditional RTS games are too fast paced for me to be any good even if i enjoy them, so the slow pace of SINS was something i looked forward to. Basically, I didn't end up disappointed. And, if after reading everything there is to know about the game, you're STILL not convinced your going to enjoy the game. Go on the website, find out if there is a Demo and if not, when it will come out, wait patiently, download, install and try. And while you wait for the demo to come out/download, you could also read the forums or production team posts to find out more about the game and maybe check out what the company policy was for Graphics. You might be disappointed by the visuals and fuming that they are severely outdated. But here's a fact you failed to inform yourself on before you bought the game. The Devs clearly state that their goal was NOT next generation visuals. THEIR GOAL was to reach a market that was as big as possible. And since the majority of PC owners have crappy or barely decent computers, they made a game that was average visually by today's standards in order to allow as many people as possible to enjoy the game lag-free, and they succeeded.
If you're wondering what's the point of reaching a mass market with lower end graphics instead of making a technologically advanced uber realistic game visually, look no further then the most fanboyed company of all time: Blizzard.
They didn't make a lot of games, their games were NEVER advanced in graphics, but they are probably the must successful developpers in the industry if you do an income per game developped ratio. That's because their games are fun and pretty much anyone that has something called a computer can play their games. And they are sticking with the same formula for their upcoming projects: Anyone who's seen starcraft 2 screenshots can tell you that the game is better looking then its predecessor but doesnt even scratch the advanced visual levels of current "next gen" games. But, it will still sell like hotcakes, kind of like sins.
Anyways, this wall of text, just to tell you that next time, before buying ANYTHING, do some research. It pays to know before you spend.
Finally a small example of ME:
I wanted a new MP3 player so i did some research last week. I could have done it the easy way and just buy an Ipod, since EVERYONE has an ipod, right? And since everyone has an Ipod it must be the best thing for me anyways. Wrong! I did some research and found out that the Ipod was bad at playing bass sounds. Sound quality is a must for me. I searched other options and ended up chosing the Creative ZEN after reading about spec, prices, and various reviews. I ended up grabbing a 4GB ZEN for 120$. Sure, 4 GB is small compared to most ipods, but the price was right, i dont even NEED that much space, i got all the features i could ever want, including videos and FM radio AND the sound quality is absolutely fantastic, the sound quality sits between my Oldsmobile Alero's sound-system quality and my X-Fi soundcard.
SO yeah, do some research, it pays to be informed.