These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Genius Bonus: In the Film, near the beginning we get a glimpse of Henry Higgins' notebook, which he's using to transcribe people's accents. It's unreadable... unless you understand the Shavian alphabet, whose creation was funded by George Bernard Shaw.
Ho Yay: Higgins and Pickering have quite a bit, particularly in "A Hymn to Him".
In its original release, Eliza came across as much more unacceptably uncouth to theatre-goers, and therefore just as bad as Henry, whereas it's getting more and more common to see Henry as a misogynistic villain putting Eliza unfairly down. Basically, they're each supposed to be a Jerk with a Heart of Gold, but current values don't look favorably on characters like Higgins.
Freddy's love-sickness and patient wait is stalking in today's terms, and while would have been seen as romantic by all parties at the time, easily disturbs people nowadays.