The detective in this is one of the better things in this, but also one of it's weak links. Then again, I don't think anyone will watch this, trying to figure out, which one is the better actor in here. Still pretty decent acting going on overall (that does not include everyone in the cast), even though the cast does not wear that much during the movies duration.
Of course, I'd advice you to watch the first one. This is already the 3-rd cash-in, though as I've said, it seems as bit of an improvement to the other two "sequels" (they are not, just re-telling the story of the first one). I wonder if a fifth part, will top the "erotic" scene with a fifth member. Then again, it was pretty obvious that one actress had a "no nudity" clause in her contract. But I don't think that will put you off.
While pretty silly (no pun intended), it might be funny at times for you, depending what you expect.