My DW has the smaller Cricut, now. But, I'm planning on getting her an "upgrade" to the Expression for this Christmas.
She has all of the Disney character cartridges. Most of them are so intricate that they're very hard to assemble at even the regular Cricut's max. size: 5.5 inches.
This weekend, we cut and assembled (she cut, I glued) a Tinker Bell for the WDW window display we're making for our Dec. trip and, even at maximum, some of the parts were so tiny it was almost impossible to glue them. I ended up having to draw in Tink's eyes with a blue pen because they were just too tiny to cut!
If you have any plans of making Disney characters, I think the Expression would be a big help.