It's very common for legacy airlines to change flight schedules. When I book a flight that's 3 to 11 months away, I expect the schedule to change perhaps only a few minutes, but perhaps several hours. In my experience, it's unusual if the flight numbers, flight times, and aircraft type all stay the same!
No, the airline doesn't owe you (and won't give you) any sort of compensation.
Here's what an airline typically will do for you if you're unhappy with the new flight time and the change is at least two hours (the number of hours varies by airline):
- If you ask the airline agent to put you on a different flight on the same airline, the agent will usually allow you to switch to a flight that meets your needs better, without any sort of change fee.
- If you ask for full refund, the agent will usually accommodate you even though your ticket is nonrefundable.
Your request has to be reasonable. If your flight now arrives 10 minutes earlier or later, the airline will take the position that you have a nonrefundable, nonchangeable ticket, and that the airline is complying with the conditions of carriage. But if the flight now arrives several hours earlier or later, the airline agent will take good care you within the limitations of what's available.
My next two Orlando trips both involve return flights that were rescheduled to 4 hours later than the original schedule. I'm really happy about these changes. In both cases, it means we can now enjoy 5 or 6 hours at a WDW theme park on our final day of vacation.