Yeah, give it a go. I have a particular fondness for character-based graphics and also pixel primitives like lines, circles, rectangles, etc (I think they're enlightening things to implement) so just give it a shot and ask questions here on the forum
If you want to render text/characters I suggest using a VGA/monospace font (there are lots of public domain ones) and converting it to a C array (that's an additional project) so that you can easily build a simple bunch of functions to display text onto your SDL "canvas". To do this you'll have to first implement a function to set a pixel though, but that's easy with SDL. If you want a VGA font already converted to a C array I can probably give you one; each glyph is simply a w*h region in what's sometimes called a spritesheet. It's not the most efficient way to do things, but who cares
Edit: You've posted another response. ncurses for the win! I wrote an entire "ascii art drawing library" (and others here might have as well), so go for it.