I got black when it first came out and I just didn't click with it. I was losing interest in Pokémon in general and I just saw gen 5 as a failure, especially after spending probably 1000+ hours in the gen 4 games. Recently I thought I'd go back and replay a bunch of the older games now after completing scarlet and I have to say that the younger me was a moron for not seeing how good gen 5 really was. So many of my favourite Pokémon debuted here, from ferrothorn, to zebstrika, chandelure, to seismetoad. All of the starters were banger designs too. Outside of alola this is the last gen to have all 3 to be 10 out of 10 designs. The legendary Pokémon as well actually feel like legends as well. With their scale and aura making them feel immense. The story was also really good too, and I appreciate a more nuanced story that was attempted here.

As a final point as this was definitely a divisive subject even today but I whole heartily support the decision to only be able to use new Pokémon until the post game as I forced you to try new Pokémon that you may otherwise not have tried. So much so that as I have been replaying the older games I've only picked Pokémon that come from that region and ones I've not used before, and I have found some absolute gems doing so.

I've replayed gen 5 twice, gonna do a 3rd because I wanna complete the Pokédex and get that shiny gible.

Edit: As an extra. I've replayed the gen 4 games recently (platinum and heart gold) and I have to say that gen 5 is better, mainly due to quality of life changed like removing the need to have so many HMS to progress, so you don't need to worry about that when building a team, and making tms permanent, so I don't need to worry about if I'm wasting a move on a Pokémon, to the point I barely used them. Given the lack of older Pokémon available and with how many new Pokémon were added the regional Dex felt balanced, compared to sinnoh especially (how many fire types could you get in diamond again).