My mother in law used to have the smaller one and ended up upgrading to the full size model. I've used it a few times and love it. I think even the Expression is too small for certain applications (like making decorative cutouts for a birthday party) so if it were me I would upgrade to the Expression rather than the personal size one. That one is really small when you might want to make letters, cutouts, etc. If you know you will only want to use it for tiny cutouts for cards and such you will be fine with the small size though.
They are very neat and you will love it! I have always wanted one to get into card making.