Here's a screen shot of an Icybus map displayed by TrekBuddy on a Blackberry 8330. The actual on-screen quality is much better. As you can see, it has many place names, and ground cover coloring. (Icybus maps also include street information and many hiking trails.)
Someone mentioned durability. This Blackberry spent 8 months sitting on a mountain exposed to snow, rain, sun, freeze/thaw cycles, and risked being stepped on by bears, mountain goats etc. After disassembly, contact cleaning, drying and charging, it revived. I've replaced the battery since it didn't come through 100%. Of course salt water would likely kill it, but I wouldn't call it fragile.
More on battery life. Trekbuddy activates with the gps reciever turned off. You can browse the maps without the receiver active, and this would greatly increase battery life. In any case, batteries are relatively cheap and you could carry more than one.
As for versatility, smartphones are an ultimate go-light gadget. In one little gizmo you can have a gps, decent camera (the 8330 has a 2Mp camera), a crappy video cam, full featured mp3 player. Some of them have radios. You can use the screen, or even better, the video lamp as a flashlight. Not to mention video replay, basic ebook, basic word processor, audio recorder and bazillions of other apps. And that's without including the phone and Internet connection features.
Here's a couple of photos taken with the 8330:
The Blackberry can geotag photos, but won't pony up the coordinates on a photo and won't integrate with Trekbuddy (yet). All it will do is thumbtack the photo on an on-line map.
The next logical step is to use a smartphone with no data or voice plan at all. You can do most of the things listed above without a plan. Used 2-year old smartphones with gps recievers can be had for $50 or less on eBay. You could get one and set up the off-line gps function. That alone would be as good as buying a real gps. And the smartphones have nice big screens. But the smartphone can do so much more than a gps or a camera. There is a huge and rapidly growing collection of apps that can do so many things it's not funny.
Because they were not intended to be used in the backcountry they lack lanyard anchors and are vulnerable to inadvertent button-pushing. But there are ways to deal with those issues.