I've held off until the second episode for an opinion, but for me the last two episodes have been an absolute joy - and something I never dared dream I'd see Doctor Who become (as long as the ultimate resolution doesn't turn out to be 'it's fixed because it's fixed' - but I don't think it can be this time

)
For many of the younger viewers I'm sure the scares and thrills, the heroism and emotion, the etc and etc (and amazing etceteras they may very well be!) will be enough even if they can't follow along. (And I'm astounded to see people posting that five or six year-olds could follow that, let alone explain it. If so I have quite a few questions for them!)
For intelligent adults who are not every-episoders, and who wish to understand things, (or at least be able to
think they understand things - which is all I ask for myself, and then even roughly enough will do), I think it's getting too complicated, even unfathomable, yes.
I think there will be those who enjoyed the RTD era who simply cannot invest enough time in this to wrap their brains around to feel they're not missing many things, without watching every Saturday night and going over and over it.
I hope I'm wrong, but huge fans like my Dad (we've watched it together since the 70s) were lost last series - he even stopped bothering to watch for the first time ever, until pushed back to it. And this series so far
looks far, far more complicated!
I dearly hope I'm wrong, but here we have a two-parter that has, imho, more questions arising from it and unresolved than from any single entire series since the revival!