For the most part, yeah! There was a weird glitch one time where I lost all my progress on Early Poptropica, but otherwise the saves have worked. The only thing I did differently the time I lost all my progress was that when I got the island medallion, I clicked the option in the pop-up box that said something like "Explore other islands." I don't know for a fact that that's what caused it, but to be on the safe side, I've since been closing out of the pop-up and manually walking back to the blimp whenever I finish an island. And I haven't had any save issues since the time I started doing that.