Whether it's "worth it" is highly if not completely subjective.
If you just look at your win rate, it will probably be pretty small over any decent-sized sample. So is it worth it to win a few cents or even a buck or two per hour? That's up to you.
Otoh, everyone has to build his roll from something, and it's better to start with money you can easily afford to lose. If that's 0, your only options are to begin with freerolls
or not to play. Otherwise, it's a matter of how much your financial situation will allow. If you're rich, you can do your learning at higher stakes, although it may still be better to work your way up starting in the micros.