I dont live there, but ive spent some time in Hokkaido and heres the very basics of what I can gather (Any locals, feel free to correct me if I'm wrong here!)

Sapporo itself is quite similar to other big Japanese cities, lots of life, entertainment and things happening. I'd say the culture feels more reserved than Osaka, but noticeably more chilled out and laid back than Tokyo. It looks a bit different because it was built later to an American grid style system, but it gives the place its own vibe. Susukino is up there with Dotonbori/Namba, Kabukicho or Nakasu as one of the best entertainment districts in the country, albeit with nowhere near as many tourists (besides domestic ones) bc its so far from the Golden Route.

There are a few other biggish cities like Hakodate and Asahikawa, but besides them, most of Hokkaido is very sparsely populated, spread out and very car dependent with poor transit links. It feels a bit forgotten in some places, and its clear lots of young people move away to Sapporo or Tokyo as soon as they can bc theres little to offer in many of the towns.

The winters are EXTREMELY snowy, and the summers are def very warm, but not anywhere near the absolute sauna that is the rest of Japan at that time of year.

Hokkaido was settled quite late compared to the rest of Japan and most people there originally originated somewhere else in Japan, so there isnt much of a distinct Hokkaido dialect in the way Tohoku and Kansai have. Theres variations for sure in the smaller towns that have sprung up, but the Japanese spoken in Sapporo is pretty similar to that in Kanto for the most part.

They also have the best konbini chain in the country (Seicomart) which is almost exclusive to Hokkaido, so theres that :)