I hated the guy when he was coaching the 49ers, but always admired his tenacity and coaching ability. The 49ers made a mistake in deciding between him and Trent Baalke. They're lucky they landed on their feet after the Tomsula era.
Since Harbaugh's left the 49ers, I've really come to appreciate Harbaugh, not only for his coaching prowess, but his impact on young players. For example, Harbaugh takes the players on a trip to a foreign country in the summer, when he could be relaxing or taking a family trip. His teams have gone to Paris, Rome and South Africa, among other places so that his players, most of whom have never left their home town, can be exposed to other cultures and learn a little history.
Of course, not every player loves Harbaugh, he's a polarizing figure. But for every former player who hates him, there's someone who loves him. He doesn't try to be a players' coach, he's very tough and honest, so he's going to have detractors.