As for the seamless tiles I agree that nature isn't perfect, but it looks very odd when there's sand/mortar between some stones and not between others (ie along the edges of each square). You should at least provide some sand/mortar along the edges of the squares too if you're going to claim that you did it on purpose because nature isn't perfect.
I agree with kent2. I really like the look and colors, but the edges are very unrealistic and squared. It is very obvious that a walk made of any of these tiles is made of the same repeated square.