Pretty in-depth review after a first playthrough. It took him about 50 hours, but he played the early access, so he breezed through the first act, and he really knows his stuff. Normal people like you and me will probably need 70-80 hours for a playthrough. The game does have some issues, mostly minor bugs towards the end of the game, and the camera and inventory system can be a bit funky. However, with all that said, it seems to be a massive game in its genre. If you like CRPGs or consequence-heavy games, you should seriously consider this one. Plus, it's woke and makes chuds seethe.
The older games run on D&D 2ed rules, and this one is on 5ed rules, so the rules are basically completely different. The older ones are good though, just get the definitive editions if you want to, there's like 150 years in between old and the new game though so they're not necessary.