The altimeter's value may depend on where you live. Here in the flatlands of the midwest mine gets ZERO use. When visiting Yellowstone & the Tetons I found it fun to watch as I was traveling.

The compass' advantage is that I can stand still and the point will continue to point in the proper direction ... but for the most part I'll only trust it if I've calibrated the compass quite recently.

I've tried to convince myself that a GPS without an electronic compass isn't as accurate when trying to find a waypoint, but with the compass turned off the GPS is still amazingly capable of pointing to the waypoint so long as I am moving even at a slow rate.

Don't sweat your mistake too much. You've got a GREAT GPS. Enjoy it.