I have 450 minutes anytime, 5000 nights and weekends, 200 text messages, and unlimited iPhone data for roughly $70 a month.
I was paying the same amount before with my Cingular 8125 and 8525 phones, so the iPhone doesn't really cost more per month.
The Maps feature is absolutely amazing. You just type in a type of restaurant or even a specific name of a restaurant, and 99% of the time it'll find exactly what you're looking for. It'll also give you Internet links, so you can even check out menus beforehand (assuming the site isn't Flash based). With the latest firmware, Google Maps is now able to triangulate a rough estimate of your position, which makes the faux GPS even more useful.