Our experience is more minimal than Val's-- we opted NOT to take a class from them when it became clear that there was:
a) not a lot of feedback from instructors,
b) not a lot of offline activity/content,
c) not a "real" lab experience associated.
This is a structural problem with a great many online science offerings, however. The problem is that an online model is often being driven by costs which promote a too-high student-teacher ratio to allow for a lot of teaching and feedback.
Secondly, the assessments:
bear in mind that students will be TAKING assessments with no way to "raise their hand" or walk up to the instructor and ask about funky questions. Assessments are multiple choice, and often very, very clearly not written by true subject experts, because they cherry-pick bizarre non-central information for questions (focusing on wording, not meaning, if you kwim), and failing to understand that at a top-level of understanding, two answers are equivalent, and that if you go to a level of understanding that makes them differentiable, you then make ALL of the selections technically incorrect.
"Lab" experiences are about 90% simulations. While that has its place, I don't consider those to be LABS so much as 'demonstrations' which are interactive. Nice to present theory, but not good to leave students imagining that things never leave you scratching your head and wondering what went wrong... which doesn't even get into the problems that Val noted.
As noted, not unique to Mizzou. We noted the same problems with Oklahoma's online offerings, and with many other a la carte providers of secondary coursework.
Local hybrid courses are usually my preference over all-online ones. My DD took AP Physics B all-online, and even with a VERY skilled and devoted teacher, it was rough. Would have been nearly impossible without help from a couple of physical scientist parents.
