We initially had tickets booked for the evening of Monday 7 March, when they had advertised having a special Northern Lights themed light show at the top in addition to the general observation deck and views. However, we arrived on the evening and were told that the outdoor observation deck was closed due to weather and that the light show had also been cancelled. They were able to transfer our tickets to the next day for us if we wanted, which we took them up on, as we really wanted to see the outdoor observation deck and glass floor. Monday night was the final night of the light show so we were disappointed to be missing out on that, but there was nothing we could do about that.
The weather the next day was just stunning and we got some amazing pictures at the top. We definitely don't regret switching our tickets! The best views are definitely from the corner where the two edges meet, and there was a queue for photos there but it didn't take too long to get to the front (about 20 mins). The cafe / bar inside also looked like a nice place to stop had we have had more time.
This was our last day in NYC so we were fortunate enough to make it up there before we flew home, but it didn't sound like they were giving refunds in this situation which would have been annoying. When we were at Top of the Rock the previous night and at the Highline during that day, we saw that there was no-one on the observation deck then either so it seems the weather makes the opening of the Edge very temperamental! (Note that the weather was dry both days and not that windy at ground level). Bear this in mind when booking in advance as you could be disappointed.