The 10/10 rating for this episode is not a mistake. It's not caused by fan-boys. It's not because of anime bias. It's because of masterful storytelling. This isn't your typical anime story that the author conjures up week-by-week to meet comic book deadlines -- AOT is pre-meditated start to finish with meticulous detail and foreshadowing.
This episode, particularly the emotional impact of it, far exceeds any and all expectations. The storytelling and manner in which the plot unfolds sets a completely new bar that I'm afraid won't be reached by other media any time soon.
If you're reading this with doubts that an anime could have such a high rating, watch the show. Pick it up right now. It doesn't matter if you like anime or not. Just grab a snack, and force yourself to watch the 20-minute-long pilot episode. AOT is nothing short of a masterpiece.