I liked it, because I felt it was in the spirit of the first. I'm a big fan of the first and this one also made me smile throughout because I felt it was in the spirit Of the first throughout.
I really liked all the set scenes which almost stand alone, such as the lamp lighters dancing, going down the bath plug hole, the adventures in the china bowl and the Meryl Streep scene.
I liked the references to things from the first story such as the bird lady, tuppence invested in the bank, the kite etc. It was really important to have those.
And of course having someone different being Mary Poppins made it different. She couldn't and shouldn't be the same, but I think she had the right smug 'practically perfect in every way' feel and being there to observe and facilitate the family basically sorting it all out themselves. I thought the main characters did well and like the cameo performance, including Angela Lansbury as the balloon lady - I know she's Bednobs and Broomsticks not Mary Poppins, but to see her there was fantastic, as well as Dick Van Dyke.
I agree that the music wasn't nearly a s good. Possibly 1 or 2 decent ish songs but nothing like the amazing list of memorable ones in the first - perhaps that was the hardest of all things to replicate?
And there were odd bits I didn't like - the cartoon wolf chase scene - just not needed. The original didn't really have a baddy as such and I don't think they really needed the Colin Firth baddy role, but it was okay. You can see it's a 21st century thing and bits don't sit well with its 1930s context like a woman being in charge of the finances, and other things which just seems to want to push today's agenda even though it's almost a century ago in setting, which grates, but lots of films seem to feel the need to do.
But overall. I smiled throughout. It was a fantastic bit of fantasy and imagining which was visually lovely (including the fab drawings of the se ends of London and the characters in the opening titles) and acknowledged what people loved about the first. You could enjoy it as a child who'd never seen the first, but it is very much a follow-on for those of us who grew up enjoying Mary Poppins and who are still nostalgic about it.