Oh man, that old penny taste is the worst. I bet you could mine copper from that filter at this point. Gotta love how "set it and forget it" really means "pay for it later with gross water." At least you're in good company, tons of folks let those things go way too long. I had a buddy who found out his was clogged after six years and his ice maker basically gave up and died on him. So hey, you're already ahead of that curve, just one less thing to worry about at 3 AM when the smoke detector starts chirping.
Did anyone else buy a fridge with a fancy water filter and forget to change it for three years straight? I just realized mine might be the reason my ice cubes taste like old pennies and sadness. Guess I'll add "change the filter" to my list of adult tasks right next to "figure out why the smoke detector beeps at 3 AM.