I was a precocious reader (<3yo), and I have a strong suspicion that kids who learn to read early read differently than those who learn "on schedule". I think early readers do something much more like code breaking, and I wonder if this affects second language acquisition or other skills. I don't necessarily think one style is preferable to the other, but I do think there is a potentially interesting difference.

I was very happy to read early, and I think it was advantageous for me, but I have not seen evidence that early reading in itself provides any lasting advantages on average. There may be a good deal of heterogeneity in the early-reading population.