If you're expecting a show that looks or feels like the original 80s-90s sitcom, which is pretty good btw (classic 80s sitcom theme song too) and you should try to watch at least some of if you can, this isn't it. The only common factor between both is that they're a class of intellectually gifted high school students. Also, both have diverse casts but the original has a wider range of characters who also seem more distinctive.
The style of the original is more like a real classroom and school, though not 100% realistic, and it is repeatedly made clear the students are above average in various ways academically. The teacher is a role model character and helping these students through their own personal issues as well, sometimes fairly serious. The style of this Head of the Class is more like Saved By the Bell (after the early years) where they hang out and chat in random scenes, rarely seen in a normal class setting, and some little story or two is playing out throughout the episode. The teacher character seems more like an older student buddy who is almost equal level as them but sometimes gives them helpful tips and encouragement.
As for the rating, add maybe 2-3 points for people under 18 as it's fairly in line with the style of comedy found on the Disney Channel and Nickelodeon, it's just those shows are hard to watch as an adult beyond nostalgia. The original aired during prime time hours on a major network and before cable was widespread so it's not quite as narrowly fine tuned to younger people and is still enjoyable as an adult I think.
