After 20+ trips to WDW, finally visited DL & DCA in 2018 as part of a California vacation. Our expectations were greatly exceeded.
There were so many things Wife and I liked. Of course being in Walt's park and seeing retired attractions from WDW we liked and expected. The convenience of getting everywhere by walking was something I hadn't previously considered but can't understate how less stressful that was. (DL, DCA, Downtown Disney, and our hotel were are all minutes from each other.)
But what surprised us most was that several DL/DCA rides were notably better than their WDW versions, including Pirates, Small World, and Space Mountain (Hyperspace Mountain!). Indiana Jones Adventure is better than Dinosaur; Radiator Springs Racers is better than Test Track. And then there are several rides that aren't in WDW at all. There were a couple rides that we did like better in WDW, namely Splash Mountain (although I guess that is moot now) and TOT (rethemed Guardians Breakout- fun but not the same). There are also more unique dining options in DW, although we ate at Blue Bayou and loved it.
Yes, the castle is smaller, but the entire park area is smaller, so it seemed appropriate as everything felt more intimate and personal. (You can walk inside the castle, which was cool.) Characters just appeared; we saw Alice and Mad Hatter get on the teacups with a little girl. The night show in DCA, World of Color, was among the best Disney night shows we've seen. As this was pre-COVID, we loved MaxPass and preferred it to FP+ (and prefer it to
Genie+, but what's done is done there); you even got all photopass photos with it!
Also, the weather was beautiful and the parks were not very crowded, although this might have been due to when we were there (September, during the week- loved the Halloween overlay). We were there two days and enjoyed it so much we returned the following September, stayed three days, and had even more fun. Haven't been back there since COVID, but from what I saw I'd highly recommend a 2-3 day trip.