I too travelled on the 27th, up to Leeds in the morning, and back in the evening.
There were certainly plenty of problems at Finsbury Park in the morning despite the planned closure into Kings Cross at that point, with many services cancelled, or being shown as running in the order of 30-60 minutes late. There was a good staff presence at that point, but they were clearly struggling to get a handle of what was going on - trains would arrive and they wouldn't know what they were doing next, some had drivers, others didn't, and passengers were told to go to one platform only for another train to appear in a different platform. The screens couldn't keep up either - quite often they would say a train wasn't scheduled to stop, only for it to pull up and load passengers - the front destination (and to a certain extent, train type) being the main clues as to where it was going.
Luckily in the evening, again, I missed most of the confusion, and the East Coast set I was on travelled straight through to Finsbury Park, arriving slightly, though not massively late. I noticed that some screens were just showing lists of trains that had been cancelled many hours earlier, which seems to be a problem in times of major disruption.
However, my overriding impression was that of admiration for many of the staff who were thrown into an almost impossible situation - I certainly wouldn't liked to have been in some of their shoes. As mentioned the station staff at Finsbury Park were trying their hardest in the face of hostility from some customers, and deteriorating operational circumstances. The driver of the 8-car Class 317 I travelled up to Stevenage was very good - informative and clear. East Coast staff were also pretty good in both directions, giving clear information on onward connections, the seat reservation situation and so on.
I also noticed some pretty slick East Coast turnarounds - for example, the service to form the 18.05 off Leeds arrived late, but was turned around in 4.5 minutes, including replenishing the buffet. Granted, there were not reservations to put out, but I thought that was still very good going.
The episode does deserve investigation, as something clearly went awry. But personally, I was an hour late into Leeds, and not too badly affected on the way back, so it's hardly the end of the world. And just to reiterate, I thought it was a pretty good showing from the staff I encountered, who were clearly trying their best.
Andy M