I love the Harry Bosch books, and love the series. Will you be disappointed? Hard to say. Depends really on how hung up you are on the differences.
Titus Welliver is not who I pictured, but I think how the begin season 1 will allow you to see how he fits. But here's where your enjoyment is make or break, when written in the 90's Bosch was a vietnam vet. At that time the cliche character from Vietnam was disheveled, mustached etc (I had pictured him as Gene Hackman- Night moves/Uncommon Valor), and the house he bought was small. In the show it takes place in modern times, and gets all the upgrades. He's too young to be a Vietnam vet, but a Vet he is, maybe Afghanistan, so the character is built differently.
Michael Connelly has been all over the series, and each season takes pieces from different books.
So give it a try, and if you can suspend the "the books were so different" vibe, I think you'll love it