Mike Kruckenberg has written an article about the question "Is MySQL Simple or Complex (or both)?" Let me give you my thoughts about that.
I think, the process of putting new features into MySQL is like giving a construction worker a new toolbox that gives him a whole variety of choices to make his work easier. But it comes with the price that it requires more advanced skills to use them.
On the other hand, he has still the option to make his work the way he was used to. It's a new choice - to use the new tools, or to not use them.
That's the same with MySQL. If somebody started e.g. with MySQL 3.x, because he liked the fact that it works simple, he can still use MySQL 5 the same way he was used to. But now there is an option to also use more advanced features (stored procedures, user defined functions, triggers, ...).
MySQL (and MySQL 5 in particular) has great options to optimize a server to work with huge loads of data (as I recently could read, multiple Terabytes) with many millions of queries a day. It can serve the largest databases on earth. On the other hand, I know some people, who use MySQL to get their "little jobs" done, without the need for advanced features. Both groups do fine and feel comfortable with MySQL, so my answer to this questions would be a clear and straight: both!
The most important message shall be: there is an option to use advanced features, but anybody can still use it as the same simple database server that it was supposed to be in earlier versions.