I would say Anima is pretty easy to learn compared to many games, but I think it could be very hard to learn for people who have not played many RPGs.
Also, I want to mention the difference in difficulty between playing and learning:
The basic rules of the game are very simple to learn and use. The dice mechanics are pretty simple and stay consistent throughout the rules. Spells and special abilities are straightforward and easy to use. Monsters and characters use essentially the same rules so the GM doesn't need to learn much extra stuff.
On the other hand, making characters and playing the game can be much harder than some games because there are so many things to think about. The first person I tried to teach the game to made a warlock and it was surprisingly complicated to balance combat, magic, and secondary abilities on one character. Making a character in D&D or Dark Heresy is much easier because you don't have as many options to choose from. Also, things like making Ki powers can be very complex.
It may be a case of "Easy to learn, difficult to master", which is probably a good thing because many of the best games in history are described that way. If you want to keep things easy at first, I recommend sticking to human characters with the simple, single-focus classes (warrior, wizard, mentalist, thief). That should cut down on the number of things each player needs to worry about while they are learning the rules.