Comfort: Yep, they are actually comfortable! Well, as comfy as 4 inch stiletto heels can be. The platform distributes the weight along your foot which really helps with the comfort. I stood in them at a bar for 4ish hours last Saturday night and I didn't want to saw my feet off at the ankles, if that's any indication.
Sizing: These run true to size, if not slightly large. I bought my normal size 9 but had a teeny bit too much wiggle room (the 8.5s were definitely too small). I put a Dr. Scholl's in them, and they're perfect now.
Hope that helps!