I have been using them a lot this year to bounce from YYZ to JFK and then meetings in NYC or connect thru to LHR or elsewhere...This winter has been the worst (in more ways then weather but related hopefully).
I would guestimate my on-time of about 20 flights this winter to be less than 30%...with 10% clear cancellations due to mechanical and a couple others due to weather.
Hope they get it sorted and I'll see tomorrow as cutting thru JFK on way back from LHR...TBD!