Wells is famous for changing the course of science fiction. Up to the time of his writing, science fiction was more about the science than it was about the fiction: a reader need but pick up one of Jules Vernes' famous adventures to see that the science is painstakingly presented as quite real, quite feasible. Wells, however, opted to go further afield, using science that was not yet possible (indeed, we've yet to invent the invisible man or a time machine, and the latter seems entirely impossible in the sense that Wells wrote of it). More importantly, Wells decided to focus on the fictional elements - his stories are not about the machines, but about the characters using the machine. He wanted to explore his characters in an engrossing plot.
The Invisible Man does not do this. The plot is boring, there's an almost complete lack of characterization besides the Invisible Man (and even his is quite superficial), and at no point in the story did I feel like something was at stake. Sure, the science of invisibility was believable enough for a layman, indeed, I'd never actually considered doing invisibility by matching the refraction of air. But that didn't cause me to care one bit about what was happening in the narrative.
It's easy to see that Wells was primarily concerned with explaining a phenomenon that would have been quite bewildering to his audience. There are long passages in which people wrestle with the invisible man and Wells describes these at great length and detail. And yet we who have seen (or not seen, as the case may be) the invisible man on the big screen have little enough need for such descriptions.
You should read this only if you are a die-hard sci-fi fan or on a quest to conquer the classics.