I thought they handled the episode better than I could have expected, with a lot of things to juggle. They just nailed the tone of it perfectly, with being a 75% nostalgia trip, with some crossover and new team arrow sprinkled in.
I binged the first three seasons right before season four. The first season was really cool, the second was truly spectacular, and then the third was so awful. At that time I was really caught up in how good the first season of Flash was, too. But anyways, season four was better than three, but still a step down from the first two by a lot. I liked how this episode really seemed to focus on the greatness of the first two seasons. It made even me, who has been super down on the last couple seasons, feel emotional. This season has gotten back to being fun again, and easily the best since the second season. It's even more fun than Flash now, which has been struggling since last season IMO because of their villain problem. Zoom and Alchemy cannot compare to season one Welles. Also the team chemistry is way off because of Flashpoint and it has really hurt the show. Even Iris being with Barry makes things way less interesting, unfortunately.
Sorry for this rant, I'm on a caffeine boost lol but my current rankings would be Supergirl > Legends = Arrow > Flash
Season 2 Arrow & Season 1 Flash are still the peak DCTV, though.