the old edge has some transparency ui effect which has it looks much closer to windows 10's design language. however, the new edge doesn't have this kind of design. the edge team can add these kind of design to the new edge , so that users may feel more familiar to other windows apps (every one likes new ui).
Yes, the fluent design is very nice so I also like it and I love watching new videos made by Microsoft about their products in fluent design. This feature is in discussion on the Microsoft Tech Community and you can also join by clicking this link.