I'm on my first replacement, batch 1541, and it froze today.
Going to keep using it to figure out if it was a one time thing or otherwise.
My last surface started out well, then during two weeks started freezing up up to 3-4 times a day while I used it. (batch 1542) Basically making it impossible to take notes in class as I had to keep resetting the device.
Crossing my fingers but somehow I think there are some 1541, more 1542s, and some 1543s with this issue.
Probably production issues or bad i7 processors according to rumors circulating.