I have the Tungsten C as well.
Tons of space on it. I have approximately 10 shareware apps and about 5 pictures, and I'm only using 4% of my available memory (at least that's what Launcher X is telling me). I will keep adding pictures for a nice photo album.
The web browser gave me problems (it conflicted with some shareware I had), so I loaded the one that came with the Tungsten T and it works great. I bookmarked the same channels as Avantgo and check them whenever I want.
The speed of this thing is stellar. Of the programs I have loaded, I don't wait for any of them to load - they're just there when I tap on them.
I have wifi at work, home, and another home - so for me I can use it as often as I want - or as little. Quickly checking mail is nice too.
Anyway, I found the review at the gadgeteer really good. Here it is if you want to check it out:
Gadgeteer Review
Cons? I don't like having a keyboard, and I would like the unit to be smaller. Also, I don't like the way Grafitti 2 makes you use like 3 strokes just to get an exclamation mark; makes me wish for the old Grafitti.