It's visually stunning, but a lot less interesting than the previous ones.

First one looked great. Then you see the second, rewatch the first, and the difference is crazy. And I have no doubt rewatching the second now would give the same impression. Except that it felt like the characters didn't improve that much, it was more like "look at this fog, look at this fire, look at this sea, look what we can do". Yeah graphics engine for particle stuff are crazy these days, the waterfall looks 95% real, fire and fog effects are great but that's a little too much in your face.

As for the story, meh. Nothing much.

You barely see how life in the village evolved, it could have been interesting but it's just a long plan of "there are dragons everywhere".

The bad guy is only a dragon hunter, sure, a little smarter, but that's it. He just outsmarts them a few times to end up defeated in a snap like it could have happened in the first encouter.

There's a looooot too much of night furies awkward flirting. Sure that's the only original thing in the scenario, but that's not enough for a whole movie. And the female dragon character is very weird. First where does she comes from ? You have this super dragon hunter that is supposed to have killed every night furies, he is super stunned to learned that he missed one (Toohtless), but it's just normal that he actually missed a second one and that regular bozos just managed to capture her ? And then the way she acts makes no sense. She just happens to do [spoiler]exactly what Grimmel needs her to do, every time. So this guy can control dragons by drugging them, so you'd expect she's controlled, but no, she just does that naturally. Which means he just freed her like that, assuming that it would just work out for him.[/spoiler]

Then there's this hidden world thing. Legendary, unknown aaaaand they just happens to find it the moment they set out for it. Actually, not even sure they were looking for it at this time, just looking for Toothless. [spoiler]There also happened to be no alpha there, so Toothless just lands there and boom, he's the king.[/spoiler]

Also about the ending, [spoiler]dragons disappeared ? So basically every dragon in the world were in their village ? There was virtually no dragon anywhere else that was not under Toothless. So where did the bad guys caught the dragons that they were saving ? There were that few when it seems that the whole viking civilization was about them, fighting against them, capturing them, etc.[/spoiler]

Could the final scene have been more cliche ? Nope, I can't see how that would be possible. So much that maybe it could be considered as intended ? Not sure.

Technically it's on the level, but apart from that, it's just a children movie, totally missing the originality and intelligence of the first two and full of non connecting story parts that can only be seen as lazy writing when you're over 10 year old. Maybe they thought the second was a little too dark, well this one is way too bland.