B.E.
I've had them for about 3 year now and I've been pretty happy. They were very heavily subsidized by our electric company, plus there were great state and federal tax rebates at the time, so I probably would up paying about half the true cost. It cuts my annual electric bill in half. During the winter months my bill is higher because of the lack of sunlight. In the spring, when it's really sunny and there are no leaves on the trees to cast shade, I pay nothing for my electricity. My summer electric bills are about a 1/3 of what they used to be. Overall, I'd say it's pretty good, but unless your house faces full south with no trees around, it's very difficult to power 100% of your usage with the panels.
If you decide to go ahead with it, make sure the installer tosses in gratis squirrel netting to keep the squirrels out. Mine did that so I've had no problems, but a friend of mine had tremendous damage from squirrels making nests between the panels and the roof itself.