I've recently been watching DVDs of "Mannix" and although I have enjoyed it, it's become clear that the earlier episodes are the best. By season three and four, the show lost some of its zing, though it was still better than the average show.
Season one is unusual. Joe Mannix is NOT a private eye like he would be for the remainder of the series. Instead, he's an agent working for Intertech--a high tech detective agency operating more like a corporation. His boss is played by Joseph Campanella and there is always tension between him and Mannix. When season two premiered, Mannix was no longer with Intertech. Instead he's privately employed and he's got Peggy as a receptionist. This is how it continued through the remainder of the series. And a few things that remain constant--Joe regularly gets the crap knocked out of him and is often knocked out (though more so in season one and two) and he doesn't particularly like women...or at least he doesn't trust them.
My advice is see season one and two and then decide if the show is worth continuing. I'm on season five and still have a bit to go until I finish.
