I just watched it tonight.
I struggle to really pin down exactly what the difference is between the good and bad Doctor Who episodes/seasons. Like if I was going to give a general complaint about this episode or season, I'd say that it felt like confusing nonsense but.... I feel like that's Doctor Who most of the time and I usually loved it even when it was in spite of the confusing bits. The more recent seasons have been confusing in a boring way that's just hard to put into words. I think this Doctor started out pretty strong but somewhere along the way it lost it's magic.
The one thing that comes to my mind as a potential difference, but honestly I could just not be remembering right, is it feels like the Doctor kind of just stands around listening to exposition a lot more in recent seasons. Like we're being told a lot more than we're being shown and The Doctor doesn't really run around solving problems as much as they wait around for the bad guy to explain everything and then we reach the end of the episode and the plot happens to wrap things up somehow. Then there is just this over-reliance on reveals of things that I don't even know why I should be surprised because it's based on some random reference from a long time ago.
There's definitely some important differences, I'm just not 100% sure that those are it or not.
Others have done a great job of breaking down the specifics of this episode. I just wanted to air my more general thoughts as they relate to the newer seasons.
EDIT: Also, whether or not the new Doctor turns out better or not, it's kind of sad to see this Doctor getting the short end of the new paradigm of shorter seasons for streaming shows. Eccleston was only on for one season and he got nearly as many episodes as this one got in two.