I still have my old circa 2000 Garmin eTrex (bright yellow!) and it serves me well. However, in the small MOLLE pouch on my backpack, I've also taken to tossing in my iPhone 4 (for our purposes, it doesn't matter if we're talking about a 4 or 5).
Since the Garmin does not have the ability to show topo maps, the phone is very useful for this. Two apps that I like are TOPO and iHikeGPS. I think TOPO was a freebie and iHikeGPS cost a few dollars. Both have their strengths and weaknesses, though you could get by with one or the other.
One concern is battery life. The Garmin can go a whole season on a set of Lithium AA's. The iPhone sucks down power by comparison. Since I do not use the iPhone for live tracking, I will put it in Airplane Mode when I don't need a location fix. This really helps and if I manage my power use wisely, I can get through a whole day of deer hunting (4am to 8pm) and still have 20% of my battery left. Obviously that's not a concern if you pack some sort of solar or battery-based recharger.
If you were really old school, you'd wander off with a compass and a sextant and some books for the sextant. Oh, and maps.
