Two features make it well worth it to me: one is that it supports spaced repetition, one of the highly recommended techniques in the "Learning about Learning" class. That means that the software, based on your feedback, varies how long it is until you see the card again, from minutes to months. It phases in the cards so you aren't overwhelmed, but have new material mixed with old. I'm beginning to have hope that i have a memory: i've just never known how to train it.
The other feature is the card flexibility. Simple "front and back" cards can be used in both directions (sometimes presenting the front, sometimes the back). A type of card called "cloze" prompts you for "fill in the blank" type questions -- multiple "blanks" can be defined on the same card. A sentence like, "An acid has an excess of H+ ions and has a pH of above 7," can be entered once, and used for three different cards:
*_____ has an excess of H+ ions and has a pH of above 7.
* An acid has _____ and has a pH of above 7.
* An acid has an excess of H+ ions and has a pH of _____ 7.
Pictures can be used. I've a custom card for people, now. I grab staff directory photos and prompt myself for someone's name, and on the same card i can prompt with a name and ask what they do, or ask what they do to prompt myself for a name.
It seems flexible enough to work through triggering all sorts of different memories, from academic, definitions, to affirmations, and other things that one might want to call to mind.