A lot of the time it was an absolute shambles. Trains showing as "on time" when they were in fact cancelled, trains showing as cancelled were running.
This is a problem at any time. When you have 'no report', most systems will say 'on time' but why can't services that run backwards and forwards have some way of being linked?
That way, if a train that will become a future service is heavily delayed or cancelled, it can retrospectively update the screens for the next service to say 'delayed', 'cancelled' or perhaps 'unconfirmed' to be more accurate (given that another service/train might be used and it still runs, but late).
Likewise, cancelled trains that might be reinstated should also have another way of being reported so not to have people leaving the station to find it turns up. Are there pre-recorded announcements to say a train is being reinstated, and if it was showing cancelled and the time passed, does it come back on the screen or become a ghost train?
These are things the railway needs to look at, because you can often work out long before a train is cancelled that it will be. At Hatfield, you can even tell when a service will be heavily delayed by literally seeing the train you're going to take going the other way to turn around at Welwyn Garden City (and such a turnaround takes a few minutes at the very least).
Despite this, you have 'On time' showing right up until the point the train should have arrived, when it begins to count up as 'Estimated <train scheduled time> + delay' which will continue to rise even if the train hasn't started! Suffice to say, passengers then lose all confidence in the system - even though it's technically correct in what it is showing!