It's not a big adjustment. The pace of movement is the same but taking stocks can sometimes take longer since edgegaurding is more involved. The biggest adjustment you'll have to make, besides learning all the new matchup, is that the control stick has some differentt sensitivities to trigger actions, and some techs are easier to perform in a way different than the easiestt way to perform them in melee. DJC for example is easier in PM with Y+tap jump or X+tap jump whereas in melee it was easiest with X+Y or just double tapping X or Y. WD OoS requires you release the full digital press on the shoulder but ton before you can air dodge, regardless of which button you use.
There's also a lot of new mechanics like B-reversals (reverse momentum), RAR (run turnaround into immediate jump to reverse direction), and others that really organically add onto Melee's freedom of movement once you get over the fact that controls will feel weird until you have fully adjusted your muscle memory (which isn't hard and doesn't take too long).