I've been 100% Apple/Mac since ~2000, so I'm predisposed to be anti-Surface, and having used the iPad at JB, there definitely is some stuff the iPad does better (notably Jepps). All that said, I'd say the Surface is growing on me and I think it will be solid. Things I can still grump about:

Windows RT is to "real" Windows like Dominos is to "real" American-style Pizza. It looks the same from a distance, but isn't. And even if it was, it would be heavier, slower, and overall not nearly as good as the stuff made in Naples (or Cupertino, as it were).

The battery logic, or lack thereof. Leave it plugged in all night in the hotel only to find neither of the batteries decided to charge because you forgot to follow all the trouble-shooting steps.

Ball notes… please.

Crashes and spinning beach balls (but the iPad used to crash as well, especially with the Comply365 app).

The combination EFB mount and defibrillator. Probably not a problem for 20 year old eyes, or those in wider cockpits, but for us mere mortal narrow-body types, I get the choice between reading at Rainman-esque distances that undershoot my bifocals or having the Surface hit the yoke in the flare… though it works pretty well if you affix it to the front windscreen. I got weird looks from the Capt and passengers when I decided just to strap it to my left leg on a kneeboard (I'd have used my right leg, but that's where my Captain America coloring book goes), but that was probably because I forgot to take them off during our inflight break.