Nice entertainment.
But I now have mixed feelings.
Eren survives with some trick, and I'll gripe. He's really dead, and I wonder on what basis that anime will hold as has been stated earlier.
When he lost half his left leg, I had wishfull thinking that with proper gear you would still be able to use that spider like device since you mainly need your arms... except bouncing off wall. But even then, we know of carbon blades that are very efficient... just not in a late medieval like setting.
Then he lost his right arm when swallowed. In fact I even wonder how he was able to save Armin at all, that part was utter bullshit.

So back to Eren making it alive:
It was nightmare. Well usual storytelling bullshit.
The injection was for body regeneration: bullshit that might fit into the setting. Particularly if that technology is derived from a previous failed attempt that created the Titans in the first place...

So now, Eren has to make it out alive from his nightmare... or from that Titan's belly.
Piercing his way out with his left hand blade when he lost that much blood and is probably suffering like Hell... or even is out cold from those very severe injuries?
Being able to pierce the back of the neck, but from inside the throat and have the Titan pop like a buble and he falls several meters?
Have Armin pop the Titan for him?

Regarding intelligence, yes those Titans have some intelligence.
They can organise their hordes for attack with specialised types.
They are also able to set traps, Eren lost a leg to such a trap.
And yes, that Giant among Titans really did target the canons and didn't care attacking Eren at all.