I've played dos and dos2 and I liked them(well I enjoyed dos's combat system more than dos2 but I loved playing them both in general), I've never played any DnD games, should I buy bg3?
If you've played DoS2 you'll find yourself sometimes conflating the two quest lines sometimes :).
I definitely recommend it
D&D is a crap system though, which drags BG3 down (but hey, I've made my peace with D&D's vancian magic at this point in my life).
To be fair though, we had our second child in September, so I'm just at the end of Act One (hoping to get some time to finish it over Christmas).