Is an overhead console worth adding?

Personally, I wouldn't bother with the added expense or hassle of installing a factory overhead console. The info given on the readout isn't very usefull, unless you just have to have temp, compass, and fuel economy readings. Besided, I'm not sure you could get it programmed if your car didn't come with that option.
If you're wanting the extra storage for your sunglasses and garage door opener I would look at aftermarket options. They'll be a lot cheaper.