I do have a Garmin 60CSx, but have not used it in for Jeep navigation for years because my middle-aged eyes simply can't see that tiny little screen. Compared to the iPad 3G running Topo Maps / Navigon,
Garmin 60CSx - $320
1:24000 maps for your area (which also includes routeable street maps): $100
iPad 3g 16G - $480
Navigon street maps: $80
Topo Maps - $8
Cost-wise, the Garmin is clearly cheaper. But with the refurb 1st gen iPad 3g selling so cheap (you don't need to create a 3g account but the gps is on the 3g chip so it has to be the iPad 3g to do the topo maps), the cost of the iPad-based solution is more modest than you'd think. Note that I did not add in the cost of the car-mounting kit for each, it's roughly the same price for each.
2) Street routing: The iPad (Navigon, rather) will talk to you to give you directions. Connect it to your stereo if you want your directions to be intelligible. The Navigon maps are updated regularly and it's a free update. Traffic can be added as a service, but that would require enabling the 3g account, which is $20/month, plus the Navigon in-app purchase. I passed on that. Because of the size of the iPad screen, it's quite easy to see where you're supposed to turn at just a glance.
The Garmin 60CSx beeps at you to warn of an upcoming turn. You must then examine the tiny screen to see where it's telling you to go. Garmin requires you to pay if you want to update your maps. Granted, you don't need to update your maps that often (every few years should suffice for anybody who's not a professional trucker), but that's still an added expense.
3) Topographical mapping: Garmin's 1:24000 maps are vector maps. They do not include all the details on the rasterized paper 1:24000 maps presented by Topo Maps on the iPad, which *is* the paper USGS topo map, just digitized. The difference is sometimes astounding. I pulled up Panamint City (Surprise Canyon, CA) on the Garmin maps, and pulled it up on the Topo Maps. There was *much* more detail available on the rasterized USGS map, including the locations of mines not even on the Garmin map. (And Garmin put Ballarat right in the middle of Panamint Lake where the old Jacobs haul road to Slate Range Crossing meets the new main road, a place where Ballarat has never been for the simple reason that it would have been UNDERWATER every time it rained hard!).
Unfortunately the registration of the rasterized USGS topo maps isn't always accurate on Topo Maps, when you move from one sheet of maps to another sheet of maps the roads don't always match up, for example, you'll see one map shifted up or down (or sometimes even an overlap or gap between them) because the registration wasn't accurate. It's usually plenty close for our purposes though.
4) Durability: The 60CSx will survive *anything*. If you have an open Jeep that you run topless through rain and dust storms and everything else, the 60CSx will shrug it off. I ran the 60CSx on the handlebar of my KLR-650 dual-sport for years, through rain, through freezing weather once (eep, that was *NOT* fun!), heck I had it on the handlebar there when I rode my KLR up the Pacific Coast Highway all the way to Washington State and back, I've dropped it from the top of a waterfall in Surprise Canyon, and you just can't break it. Vibration, baking sun, freezing rain, it shrugs it all off. If you run a topless Jeep, get the car kit with the 12v power cable and the suction cup mount for your windshield and you're all set. If you want to get fancy, get a RAM U-bolt instead and mount it to the passenger grab handle, get a long stalk, and get the RAM cradle for the 60CSx, this'll help damp the vibrations a bit (this is basically the setup I ran on my KLR which vibrates a *lot* more than a Jeep). And the 60CSx will clip right to your belt when you're ready to start hiking too. The only problem is that a) the screen is tiny, and b) the maps are mediocre at best. Which is why my 60CSx annoys me and I rarely use it, instead using my iPhone or iPad in the Jeep and a Delorme PN-60 when hiking (which has an even smaller screen than the Garmin, but much MUCH better maps).
The iPad is quite durable for what it is, it doesn't mind vibration and it doesn't mind dust on that fancy touch-screen (that guerilla glass they use is *tough*) but it is *not* waterproof so you should not run it in a topless Jeep where you may get rain. It is also not dustproof, though mine got covered with dust pretty well during my last two Death Valley trips and it doesn't appear to have harmed it any. One thing the iPad *did* let me do was avoid taking a computer with me altogether on my last two trips -- there was no need, the iPad would read email and browse the Internet just fine, as well as let me read my eBooks in my tent at night. Note that the 3G connection, if you choose to enable it, is month-by-month so you can enable it for that big trip to MOAB and then disable it after that, but the WiFi works fine with typical hotel WiFi connections.
So anyhow, that's the comparison from someone who actually owns both of these (plus a bunch more) and has used both extensively. For what that's worth. After all, everybody knows that second hand information from a friend of a friend is much