I have a iPad to use with students, and I'm still not convinced of it's usefulness, mainly because on it's own the iPad is not a great tool. Instead, it is the apps that will make the tool valuable, and I just don't have a good sense on a lot of good tools right now.
What my students currently use it for:
We primarily use the iPad for three main uses: Qwiki for research, kidblog for student publication, and IXL, a website for math practice. The students will also use a dictionary app and safari for research. I haven't found many apps yet that seem to be that useful for 4th grade, particularly when I only have one.
What I'd like to get more of:
I'd like to get an app for grammar practice, concept mapping and reading support. I'm sure they are out there, I just haven't found anything yet.
Issues so far:
I have had issues with students playing around with the settings of the iPad, which is unfortunate. I should have spent a little time discussing what they could and couldn't edit. I'd love a way to lock certain apps, like photobooth, as when students should be practicing math, they are playing around with photobooth. Next year, I plan on being much more careful with how I present the iPad to my students.