I got my Air 4 on Day 1 release and just love it. In essence it is the same as a Ipad Pro 2018/2020 but without 120 mhz screen, 4 speaker stereo and Face ID. You still get very good 2 speaker stereo audio , and power button Touch ID which is exclusive to the Air 4 at the moment, and works perfectly. With the Air 4 you also get the modern and more efficient A14 bionic chip which gives you faster single core performance on par with the new M1 chip and also superior neural engine machine learning, so will feel snappier in day to day tasks than the A12 X/Z in Pro 2018/2020 models. GPU performance is about equal, but the Ipad Pro 2018/2020 will perform about 10% faster in multicore processes due to having 2 extra cores. The 2021 M1 Ipads offer more performance in every metric though.
The Air 4 can also use all the same peripherals as the Pro models, like the Magic Keyboard and Pencil 2, and also uses the same USB C port for connecting drives etc. In terms of the screen, i think i got lucky with mine as it is almost perfect with no light bleed that some other members have had, and side by side to an Pro 11, the liquid retina screen is practically identical in terms of colour accuracy and contrast etc.
Overall though, the Air 4 is a fantastic ipad that will please the vast majority of people, as Apple designed it this way, to appeal to the masses at a reasonable price. You even get 5 colours to choose from, even Rose gold (basically pink).