There are a large number of considerations when it comes to changing companies and jobs and whether you should do so or not, all of which will take careful thought and consideration.
One obvious thought is with regard where you will be based, working hours and patterns in the new job, and any problems this could cause with your home or family life.
Most people think about the money they will be paid so remember to check that this is tempered against working hours and lifestyle in the new job, and also that you should consider things like holiday entitlement, benefits such as private healthcare, car if relevant and also of course pension which is particularly important - see how much the employer contributes and if they will match your contributions, all very important questions to ask and consider.
If you have decided to move then you might have an exit interview, where your current company finds out why you are leaving, and this is often then fed back to their HR team to monitor why people leave and identify any common trends of patterns.
Remember that you should be paid for any holiday entitlement that you have but have not used, and that you will probably be required to work the full period of your notice, so if you need to give three months notice then you will need to work for that period of time before moving on.