Sword Art Online is an amazing anime, it absolutely on another level, at least the first half is.
Sword Art Online is a 25 episodes long anime. There are two story arcs. Each arc covers roughly 12/13 episodes.
The first half of the episodes cover the Sword Art Online plot, while the second half of the episodes cover the Alfheim Online plot.
During the Sword Art Online arc, players are trapped within the game system and are unable to log out. Players who die in game will also die in the real world. This gives a real sense of danger and brings reality to games. Due to this gameplay, players panic and are reluctant to adventure, since one wrong move is a deadly cost.
Then comes along, the main protagonist, Kirito. Kirito is very skillful and often acts alone but successfully. Whatever he sets his mind to, he will achieve and does so in an epic manner.
A lot of the fighting is done very well. Kirito often emerges as the victory. Though he does have support from Asuna, the female lead and also his in-game wife and real world girlfriend, Kirito is composed and uses his dual welding swords as an advantage.
Over the course of the anime, especially during the second half, the pace is much slower, and it loses its special touch. In the Alheim Online arc, players are able to log out and dieing in the game is minor.
We would have loved to see more suspense or a story built entirely in the Sword Art Online instead.