This study seems presumptuous.
1) My wife, a statistician, gets irritated when studies say that they have proven things. When trying to draw conclusions from data you always run the risk that your data is not indicative of reality. You get around this with large sample sizes and by receiving data that points to the same trends on repeated studies. This study has a small sample size, 26 people total, and has no mention of repeated results.
2) The friendly article claims that the study has "proven" that action games train people to respond quickly and accurately. The article is overstepping the study in that the conclusion of the study was that people who play action games had the same level of accuracy as those who played The Sims II. The article should have said "quickly without losing accuracy".
3) The author of the study claimed that "People who play these action games make informed, better decisions than those who don't". The study only compared people playing two FPSs to people playing The Sims II. There is no mention of a control group that did not play any video game. The conclusion needs to be a bit more humble and only make statements between people who play FPSs and people who play ... whatever narrow genre The Sims II falls into.
I frequently enjoy Alien Swarm. I played Portal and my wife and I are slowly meandering our way through Uru. I used to be hooked on Starcraft, Myth II, Myth, Master of Orion II, and others. I believe that these games have shaped my neurological development and given me advantages in problem solving, strategy, coping with unexpected setbacks, and more. I also believe that they've cost me in self-discipline, my attention span, humanity (desensitization to violence and beyond that enjoyment of violence). My point is that I want the conclusions of this study to be true to give some legitimacy to what is otherwise an unproductive diversion but the study feels a little shoddy.