Mark is right on the money with O-107; easiest quick diag is star points into cap above forehead. PCGS calls this one AU55, which I think is a fair grade. Of course, the coin "is what it is" regardless of their opinion. My first CBH, way back when, was an MS62. I had this absurd notion that MS coins are better than circulated coins. Not necessarily; that 62 was dull and lifeless. Due to poor strike and worn dies, it had about the same detail as this coin but nowhere near the eye appeal as this one. I think lustrous natural coins are the ticket regardless of TPG grade.
RLM's point is well made; it's very tough to grade from photos, and very tough to discern rub vs. Worn dies vs. poor strike on these early federal coins. As mentioned above, I once had a CBH slabbed MS62 with about the same detail as this one.
900, 55 is definitely a fair grade for that nice half. How many lights did you use to photo that thing? I ask because it looks like just one, what James Garcia calls the SOLB method (single overhead light bulb). In my opinion, you need at least two, and preferably three, to capture a coin like that and light the entire surface. That would take care of the darker areas, and I'm guessing more people would have accurately guessed the grade.