Tiny Core Linux is not a traditional distribution but a toolkit to make your own system using components only you really need. True, it is fast and small with unique features. One of them is that system is not installed on the conventional way. Applications resides in read only extensions and mounted at boot time. Changes, home dir, etc. reside in RAM and by default not restored at boot, so you have always a clean environment which makes it ideal for development.
Of course, you can save data, you can have a traditional persistent home dir, what ever you want. Tiny Core Linux (and piCore) offers much more freedom and flexibility than any other systems. It fits really to Raspberry Pi, ideal for education, hobbyist, etc.
Basic system is CLI only. You can install required components. You can stay with CLI with servers, SSH remote access or install X with a minimal graphical environment with flwm window managers, indtall LXDE, etc. Anything what you want.
If you are looking for just another distro, probably it is not for you. If you have a special project, you are learning LINUX, curious what is inside, lets go.
Note, it is a still beta, repository is growing day by they. Contributors are welcome to join the project.
To learn what is it, visit Tiny Core home page and read intro:
and core concept: