LOVE IT!!! Worth every penny.
When you consider it's less than the price of a cartridge, it's a bargain, in my opinion. It is incredibly easy to use right "out of the box," so to speak for fonts. Shadowing is just a click of a button and welding is very easy also. I downloaded the free-trial of the Design Studio and I found it kind of a pain to use. SCAL is much easier.
If I were to choose between the 2, I'd go with SCAL because although you can't weld/manipulate your Cricut fonts with it, there are many free fonts online that are very similar to Cricut. Although I can definitely see the advantage to having both, if you love your Cricut carts.
As far as images go, the possibilities are endless, I'm sure, but that's one thing I haven't really delved into. You can cut any dingbats as is, but in terms of more complicated images like jpegs/gifs/etc you need to first convert them into a file SCAL can read (SVG). You do that with the free program Inkscape. I'm sure it's not hard to use, but I haven't yet had the patience to sit down and learn how to do that. There are tons of free tutorials online though that will walk you through it. Basically - yes, you can take a coloring book type image and break it apart piece by piece to do your own paper piecing. I think some other people here have done that already - hopefully one will respond.
Also, if you're lazy, like me, and not opposed to spending a few dollars, you can also buy (or download a free one) a file for the Wishblade/Craftrobo machine. You still have to convert that to an SVG file but that's very easy - you just need a couple different free programs installed on your computer. I wanted silverware for one of my swaps, and I tried to make one myself but I just got too impatient and bought a Wishblade file for $3.
I got it mainly for the fonts and I am 100% happy that I did. It is just so much fun to see what you can create with it!
Some helpful sites I've found:
The SCAL forums:
http://forums.surecutsalot.com/
This blog has tons of tutorials and step by step instructions:
http://www.susanbluerobot.blogspot.com/
How to change Wishblade files to SVG files:
http://forums.surecutsalot.com/viewtopic.php?f=17&t=817&hilit=gsd+file
