The Expression2 has a small touch screen that you can use.

Both can be used with the Cricut Craft Room online

Both use the same cartridges - you can only cut from cartridges or digital cartridges purchased from Provo Craft.

Happy Crafting!

I love my Expression. I've had it for a few years, and just love that it cuts large shapes (the original Cricut only cut up to 6x12, but the Expression (E) cuts up to 12x24.) Since I scrapbook and make cards, the larger size is great for pages, or home decor projects.
Personally, I have never used the E2. I have never had any problems with the E, and I am one of those "if it ain't broke, don't fix it" kinda girls. I have no need to upgrade to an E2.
The E has so many awesome features- you can use arrow keys to cut at just the right spot on a paper. You can cut as small as 1/4 inch (although I have never cut anything that small), and you can go up by a tenth of an inch. So layering is really easy.
Usually, I tell people to read all instructions before using a product, but with the E, I was able to use it out of the box. All I had to do is figure out how to put in the Blade Housing and a Blade, and the rest was self-explanitory. There are also YouTube videos that can be helpful. The only thing I think is worth reading up on ASAP is how to change cutting settings (ie for thicker paper, or very detailed cuts).
I would say you picked a very good machine. It can be used through a computer (Cricut Craft Room) for more design possibilities. Cartridges can be found on sale for under $20 at craft stores. Most cartridges have a good assortment of designs. I own 8 cartridges, and have yet to find a shape I needed to cut and didn't have. The big cost of maintaining my Expression over the years is paying for new blades and extra mats.
If you only have one mat, it slows you down a little. Two mats, one can be in the E cutting, and the other you are peeling off the cuts from. Three mats is more than enough to multitask.