Having a custom rom is an amazing, incredible thing.
For one, almost every carrier includes a crap load of bloatware apps and bullshit that you will never use or need, and makes it impossible to get rid of. For me, this alone is enough to want my own custom rom.
But you also have the benefits of being able to completely customize your phone to your liking. From the UI itself, to how the hardware performs, you have control of everything.
Google has removed a lot of nice apps from the market, like adaway for example. But with a rooted phone, you can easily sideload the app and then install adaway to get all ads off your phone. That means that even when you have a FREE version of an app that comes with ads - you get the benefits of the PAID version of the app (no ads.)
That's just one example of the benefits of rooting.
Rooting/ removing security, and installing a new rom isn't the most fun process, but the thing is, you do it one time, then you're done. Once you've done it one time, it's like riding a bike if you ever need to do it again.
Now to answer your question: "is it worth it." This is only something you can answer. Honestly I don't see why anyone who has an android wouldn't want to. Sure you MIGHT void your warranty, sure you MIGHT have to learn a few new things about your phone, but IMO, the benefits outweigh the cost.