Absolutely love this; one note; sometimes after saving the changes and go back to change say one character or a line, it doesn't popular "save changes". Maybe a small bug? In either case, I use the plug-in for every WP site I run and can't live without it. No more going through different theme menu's just to edit the CSS!
This is the kind of plugin you'd easily donate $10 for because it's so useful.
Much thanks to WASP Themes (creators of the Yellow Pencil plugin) for offering such a lightweight and useful tool for nothing.
If you use custom css to regularly style elements like I do, there's nothing quite like being able to preview those live changes in the window while you code.
I've been using this for about 16 months, I use it on over 10 different wordpress installs to cleanly and effectively make simple color changes, add padding, etc.