Its nice to have each mood level have a suggested name, but also to be able to change those names to be more appropriate to you. For me, its easier to have a word describing my mood than just a number.
I like that it stays on your device, too. You can back it up to Dropbox too, but you have to do it manually.
It has a nice feature of letting you see your average moods by time of day, which is pretty interesting.
Hopdude about iMoodJournal - Mood Diary