I think that what is getting lost a lot is that when shows are rebooted, it's done for a new audience, not the same old one.
As such, I'm basing my review on the audience for this new show: young kids whose parents and teachers have grown up watching the original.
My kids are 7 and 4. The elder one was initially exposed to Magic School Bus through her teacher showing the original series as a treat during the very rare "pajama day" at school. The younger one was only exposed to the original insofar as the older one wanted to watch *more* Magic School Bus.
They both love the reboot. They ask to watch it over the original, which the older loved, but which the younger hated because it was "too scary". The reason it was too scary? The kids in the original would be yelling in fear over something every two seconds. In the reboot, the children are on the whole more competent and calm, and overall freak out less. When they find themselves in trouble, they try to figure out solutions on their own before appealing to Ms. Frizzle for help. I can see how it's more appealing to young kids who have grown up being told that anyone can do science, and that unexpected events can be an opportunity to problem solve.
As for Ms. Frizzle? I happen to like that she's not a carbon copy of her big sister. Yes, sometimes her puns are very random, but I think it works to give her a personality of her own. Mckinnon doesn't quite disappear into the character as Tomlin did, but I think for my part it's because I was familiar with her voice beforehand, whereas I didn't know Tomlin before watching the original Magic School Bus. My kids have never heard of SNL, so they don't really have any way of recognizing McKinnon's voice, as it should be. To them, she's just "the new teacher".
If you have kids between 5-9, they'll probably enjoy it regardless of whether they love the original or not.
