The summaries of the previous posts are excellent. I would make a few quick bullet points.
To be completely happy,
1) The EV should be your second car... That way you can use it for trips that are no more than 50-60 miles (for the original 24KWH battery). For longer drives you take the gasoline car.
2) Expect to drive at the legal highway speed limit (or less) to not drain the battery excessively fast, thus reducing your range. If you expect to drive the car at 65-80 MPH... Then DO NOT buy a Leaf.
3) During hot/ cold weather, you cannot blast the A/C and Heat, or your range will be cut in half. The air and heat work fine on the Leaf, but it must be used in a moderate manner.
4) If you live in the mountains, with long distances and high elevations, do not get a Leaf. In order to climb high elevation changes, the car must use much energy, thus lowering your range.
5) You must have a driveway with an electrical outlet to charge over night. If you live in an apartment and park on the street, with no outlets around, do not get an EV.
I live on Long Island, NY, and drive an original Leaf (24KWH). I am able to drive the entire length of the island with my Leaf, sometimes stopping for 1/2 hour or so to quick charge the battery to get home. I own the car, love it, and expect to put 200,000 miles on it eventually. So...