Is Attack on Titan a good anime?
The basic story-line of Attack on Titan is simple: main characters fighting against titans to save the world.
Is Attack on Titan a good anime?
Well, it depends on what kind of genres you prefer.
Drama? Mystery? Or Action? Suit yourself.
Benefits of watching Attack on Titan
Those with strong stomachs (or those who can put up with cruelty and insanity) can enjoy watching this anime, since it gets quite gory from time to time. (Just for your info, the manga is more graphic than anime. There is hardly any sexual content though.) For instance, the protagonist of the anime, Eren Yeager, vows to "kill every last one" of titans after watching his mother getting eaten by a titan. Basically, no character in this anime is safe from being killed.
If you like anti-hero films, I also recommend you watch this anime. Just as Shinji in Evangelion, main characters of Attack on Titan are not typical heroes; they are more like cowards. So you can sympathize with these characters when they get frightened by giant titans. You can feel that fighting isn't some sort of game or sport and thousands of people will die eventually. And the fact that you can die next time always lingers in back of your head after watching these episodes.
The anime also deviates from cliche. Characters that vow to themselves that they will never die eventually perish from scenes regardless of their high morale and goals.
If you want to feel a medieval European vibe, just like Berserk, This anime is also worth watching.
The OST (soundtracks) of the anime is also remarkable.
Bad points of Attack on Titan
Now, I have to point out bad points. Yeah, there are many:
The protagonist himself is a shit. You'll wonder why he is a hero while watching episodes. By the end of Season 3, you'll realize he was never meant to be a typical hero.
Main characters' two best friends are shits too. They always stick with the protagonist, so you'll watch 3/4 of the show with shitty feelings.
The character development is also really terrible. The anime keep saying side characters' names, but you'll forget them soon after, because the anime does not cover side characters in depth. So in the end, you don't even have a clear idea of who they are talking about.
Flashbacks are unnecessarily used in many scenes so sometimes it's stressful to watch same flashbacks repeating over and over again.
The Best Season to Watch
That being said, I think Season 1 is the best. As you all know, the starting point is often the best. This Season is also more lighthearted compared to other Seasons. You will be amazed by the dark tone of Season 2, 3 and 4 after completing Season 1.
Season 3 part 2 is my second best. I can say that you don't have heart if you don't cry by the end of Season 3 part 2.
There are side series and a live action film, but I'd recommend all of you not to waste your time on these.
Last but not least, these are just my recommendations.
First watch it and decide it for yourself.