I will keep this relatively brief.
I absolutely adored the first 3 seasons of Attack on Titan. I thought it had a lot of spirit and atmosphere, and it made waves among the anime world, and justifiably so. However starting at the final season things really just started to go down hill. The art style was completely changed because of a change in companies and instead of keeping things faithful they decided to abandon it for something that was worse quality. This include worse usage of CGI than in prior seasons. Similarly, the animation quality dropped off between the third and final seasons. The soundtrack fails to have some of the subtly and variety of the previous shows and prefers to be more "In your face" almost all the time. The OP and Endings at this point have tried to copy the success of the first to the point where they are not really at this point "Unique" or particularly different, just more of a worse copy.