It's not. While the campaign certainly sets you in a place that would be appropriate for a tutorial it does little else than that. You get your hero, land on a beach and that's it. It doesn't say anything about the controls or what you should do next. It simply throws you into a game that, let's not forget, has a very steep learning curve and expects you to know everything from the start. Now, that might work if the manual actually explained what makes the cogs spin instead of breezing through every subject.
I know there's the Civpedia-like dongle but the game never tells you it's there. I found it by accident after good two hours of playing.
I don't know what in-game text tutorial you mean and I hope it's not the very brief summary you can find in that encyclopedia because it tells you virtually nothing. How the hell should I know that there is a possibility of buying items in the towns for your heroes? The option is buried so deep in the UI that you simply can't find it if you are not aware where it's located.
The whole interface screams lack of polish. Even the cursor is buggy and doesn't always work like it's supposed to, for example when assigning points at the level up.
The game's biggest sin, though is, as I said before, it's stability and performance. I had it crash on me while leveling up, when entering the combat, when exiting the combat and even while trying to access my sovereign's items. I read on the forums that's very common for the ATI users so it's not an isolated issue. This and the performance getting reduced to a crawl in the later stages of the game.
I love the core concept, I love most of the ideas but the execution is, so far, very mediocre.