Hate that Sword Art Online receives is often generated from what many people believed it offered. Initially, Sword Art Online appears to address the question of how a society functions outside of reality--inside a game; however, this is not entirely true. While it cannot be seen in the first few arcs, Sword Art Online's overall theme is not about what happens to a group of people who are living inside a game, but rather it is about what happens to those people when they get thrust back into reality. Unfortunately, the anime stopped the story short, and this plot was never addressed.
Also, Sword Art Online is very subtle in its explanations. Don't watch this anime and expect it to give a reason explicitly like traditional shounen anime. Answers are there, but they are touched upon thereby forcing the viewer to fill in the gaps. These gaps, however, are not large. In fact, actively watching and closely paying attention will make these jumps very simple.
In conclusion, Sword Art Online is a very enjoyable anime; however, it is neither a turn off your brain and watch show nor a sit down and discuss the implications of the plot show (as of this point at least). Instead, it is a show that forces the viewer to focus and to think, despite its generic appearance.
