I was booked in F on this flight, and I thought that it was handled well by UA.
They made the decision to cancel it 2 hours before scheduled departure, and this left enough time for some alternative routings to still be possible. I was in the C gates IFL and was paged to reception.
I was offered:
1. Business class on the BA flight direct to LHR (BA had no F availability).
2. F class with UA to FRA, and a connection in business to LHR
3. Hotel accommodation and meals, and remain with the flight.
I took option 2, and as I type I'm waiting for my bags to be delivered to my house (UA @ LHR called to say they would be here shortly).
Not really sure what else UA could have done given the circumstances. ( & thanks to the UA IFL staff who were very helpful).