I was only mildly impressed tbh. It feels like ever since gen VI they've been doing an awful lot of this "LOOK HOW BIG THIS FRANCHISE IS! LOOK AT HOW MANY REFERENCES WE CAN CRAM INTO A MINUTE LONG VIDEO!" compilation stuff. It's like, yeah, we get it. Pokemon has a long and storied history, how about you put more effort into the now instead of constantly masturbating about the past? Oh right, nostalgia sells...
On another note, it's yet another frustrating tease that they could make a different anime as an alternative to the ever droning Ash "saga" (though not THAT flashy for the whole thing obviously) but just like Origins, Generations, the Galar specials and more, it's just that. A tease of what older fans would like to see that they'll never fully deliver on.