Definetly worth it.
As an aside, I'll share a personal experience.
Last year, when I was getting ready to write the MCAT for the first time, I came on here and almost everybody was against taking a prep course. I was fresh out of sophomore year and pretty happy with my 3.7 GPA 🙄 and figured I could handle the MCAT by self-study with old TPR review books. I should've checked into it more and not been so naive but I just went ahead and didn't take the course. In the end, I got a bad mark and had to re-take this summer.
This summer, I decided to take the Kaplan class and it paid off bigtime. True, the instructors will vary in their teaching ability, but the 11 Practice Tests and tons of other practice materials are worth the hefty $1500 pricetag.
Ultimately, I'd say take a practice test and see where you're at. If you score <30, I'd recommend the course. If you're at 30 or above on the diag, then you obviously are at an advanced level and probably need to just brush up on some content with some old review books/take some more Practice tests.
If you do take the course, make sure to do all of the homework and all online materials (TWICE, if possible!!). The in-class instruction just scratches the surface and just makes sure everybody's on the same page.