If you fish the same familiar waters all the time, GPS isnt worth it for you. You probably now the lake enough to get by.
Gps is fine and dandy, but the Unimaps it comes with are worthless, and NAV Chips are way over priced.$199 bucks and up. If you have an I Phone, the Navionics app available for them is inexpensive and quite good.
Get something with a decent sized screen, dual beam, color or gray scale, up to you. Lowrance or hummingbird, they all have good and bad points, i have one of each, and prefer the lowrance.The humminbird is a 586Ci, and i cant aford or dont want to pay for the chips, so for me, i wasted money for nothing.
TrackMaps give you most of the info GPS units give you, and you can plan your day in the comfort of your livingroom before you leave the house.
It all depends where you fish, and how you fish, that will determine what you NEED.