Initially, Holling thinks that Mrs. Baker hates his guts. The feeling appears to be mutual. The special one-to-one sessions he is forced to have with her are no such thing. To Holling, they're a punishment and a form of exquisite torture inflicted on him by a mean, sadistic teacher. Holling greatly exaggerates, of course, but there's no doubting his genuine loathing of Mrs. Baker.
In due course, however, Holling comes to realize that he had gotten Mrs. Baker all wrong. She never really hated him at all; she just wanted to instill some discipline into him. She also wanted to broaden his horizons by teaching him Shakespeare, which to Holling was even worse than doing menial chores. But thanks to Mrs. Baker's patience and persistence, Holling comes to develop a great love and appreciation for The Bard, which makes him look forward to his Wednesday lessons in a way he never thought possible.
On a personal level, Holling also sees a different side to Mrs. Baker. He sees the real person beneath the rather forbidding exterior. Holling eventually sees that Mrs. Baker is a good person and someone to be trusted and respected. Holling even goes so far as to pray for the safe return of Mrs. Baker's husband, who is missing in action in Vietnam.