I have made a level 1 Investigator which I played in PFS last week and I'm looking forward to playing him again this week. He's a tiefling with claws and a sword cane. I used my 2 infusions for shield. I landed some hits in combat. It was fun and I liked the inspiration mechanic a lot.
There was no combat flavor however, and I feel (still) that the class does not have an intuitive play style. I don't immediately "get it" when I consider how this class is meant to perform in combat.
Studied Combat and Studied Strike help, for sure, but they arrive WAY too late at level 4. In PFS terms, level 4 means I have to get 9 games under my belt before I have enough experience. To break it down further, 9 games means that if I play once a week, I'm looking at just over 2 months(!) before I can use the Investigator's signature combat mechanic. Can you imagine?
So, my feedback for now is this: yes, the class has a lot of flavor and opportunity for fun play but it doesn't start until level 4, which I feel is much too late. I have to add my voice to those saying Studied Strike and Studied Combat need to come at level 1.