niece of mine (13) who started recently with photography (even took a 1 week photo-course of some kind) would like to try a classical Polaroid. Now - I know that there are different models like SX-70, and different cameras in 600 format - what would be the best choice for her? I have personally never shot polaroid so I do not have any personal experience.

As far as I know there is just the impossible project as a source of film and it is not cheap, but I could get here a few packs to get the taste of it.

Are there any significant differences between the cameras? I would like to find something user friendly-ish if possible ...