I'd say the $150 was more than sufficient. Schedules aren't even guaranteed, if your flight from the original gate was delayed for the same hours you waited, they would owe you $0. Not updating the board and doing it verbally is pretty lousy and that's probably why they agreed on a customer service gesture to you.
Heck, I've read BA passengers with no IFE over the Atlantic get 5000 Avios. What's that, $50?