The art is a little shaky in the beginning but looking through your later pages you've improved a lot! Rosie has a really unique and recognizable character design. And she looks good in a lot of facial expressions. I really like it.
Though even in your latest pages though there are a few art choices that stand out to me as odd. For example, I notice how people sometimes have shadows but mostly don't? It looks wrong to me- like the characters were photoshopped in instead of being present in the environment. Also speaking of environments, it's clear you like drawing people way more than you like drawing backgrounds. And the people do look kind of flat sometimes, but nothing you can do about that except practice.
About the story: the beginning comes off to me as kind of trope-y? The weird dream, "no time to explain," the mirror mcguffin, and "it's dangerous to go alone! Take this!" are all things I feel like I've seen before. But that's not necessarily a bad thing- I will read tropey stories, as long as the tropes are ones that appeal to me. And judging by the comments you have found people who are into it!
If I just stumbled across this comic, I probably would only have read it if the art was more confident or the story was weirder, I'm sorry. But that's just me, I prefer weird stories and judge art styles harshly.
You're clearly improving, though. If you decide to do another comic after this one ends I bet you'll get a lot more people.