I've never tried one, but they are included for exactly the reasons you give; i.e. not wanting to have to micromanage your character. I'm pretty sure that you can tailor them to work exactly the way you want, or to get an idea of how the default one will work. Try taking a look at your character screen and then checking out how the auto-leveling scheme will work.

The big downside to an auto-level scheme would be that it might prevent you from getting certain abilities or spells that you really want. If you're excited about a specific spell or tech item, or about using a certain type of weapon, it's probably more efficient to allocate points yourself, since you will need to first boost the prerequisite stat and then the skill itself. For example, to get a high-level tech schematic you will need to boost your Intelligence and also get all the lower-level tech schematics in that college. To get that tech as fast as possible you will want to make sure you allocate each point just so, whereas an auto scheme might spread your points out a little more.

Arcanum is the kind of game where you're going to want to try out different characters because the game reacts very differently depending on how you play and what you do, so I would say go ahead and try out the auto scheme and see how you like it. If you're not enjoying it, restart and try a new character. The most important thing is that you have fun!