Not as bad as a lot of people are saying it is.
Is it as good as Riders/Defenders Of Berk or Race To The Edge? Of course not. It is it’s own thing.
It’s not taking continuity of the movies and tv shows prior and mocking them, but rather giving us the viewer a glimpse into a different crystal ball where 2 kids can magically talk to dragons. It’s just a harmless sorta what if type of thing.
The animation however is a bit disappointing and it does look cheap (especially in the human characters). In the previous Dragons shows there was a very good attention to detail and the texture and colors on everything nearly matched that of the films. Here it kinda feels like most of the animation crew just either left the project or were just too busy with new projects. Shame.
Overall, worth watching to form your own opinion. You should never ever go by what critics or Rotten Tomatoes have to say about something you want to see. Just click it on and you be the judge.