Well to answer you about why the show was praised - it was only season 1 that was praised. And I understand the people who praised it, because myself when I saw season 1 I adored it as a fan of the novel.
Fuller and Green are known to have an excellent style, a great creativity and to have the ability to cast wonderful actors and they did just that for season 1. Season 1 was not a copy-paste of the original novel (but that would have been boring and unpractical), but it was faithful in that they managed to update the characters to the screen and to modern times in fascinating ways, and they also perfectly got the tone, feeling and magic that was supposed to be carried on. It was something fresh, new, updated, but faithful to the novel.
Problem is: adapting AG in such a unique way was something only Fuller and Green could do. Once they left, I kind of knew personaly the show was done for. I still looked at season 2 because there were elements left from Fuller/Green and not everything was to throw out - but in season 2 the new showrunner was not so much trying to adapt Gaiman's novel than to develop and expand on what season 1 had created. Season 3 promoted itself as "much faithful to the book" and "returning to the novel" after season 2's complaints, but I watched it and I can tell you, only a quarter of season 3 actually adapted the novel, so I honestly don't know if the people who made season 3 even read the novel...
My opinion: if Fuller and Green had stayed, the show would have been badass and great. Problem is, they only did season 1. So only season 1 is badass and great, and all their plans for future seasons were thrown in the water. (For example, one of the things they added in season 1 was the greater presence of Audrey. In the novel she appeared two times in the story, but these two times are key events in Shadow's life, so Fuller and Green decided to flesh out a bit Audrey's character by giving her more scenes, and they wanted season 2 to have a lot more Audrey scenes, they told us so. But none of the other showrunners have picked up on that, and Audrey was entirely dropped.)
(Same thing with the aliens. Fuller and Green wanted to introduce aliens among the New Gods, and they prepared it with the "there are starmen in the sky" line by Media. In fact, in the first episode of season 2, Shadow is kidnapped by an UFO-style thing, and given this episode was actually a Fuller and Green script being recycled, it is clear this was part of their plan to introduce aliens. But since the other showrunners had other plans and ideas, the aliens never appeared).
But yeah, this is the major trouble of this show. Each season's showrunner had a different view of the novel, and wanted to move the story in a different direction, but as a result this leads to them constantly abandoning or changing what had been established by the previous showrunners in previous seasons ; and it also lead them to go further and further away from the novel.
But yes, honestly what most people praised was season 1. It was the start of a great adventure, but it was cut short, much too short. Already season 2 was very divisive, and then season 3 was completely abandoned.