you shouldn't really compare BG3 to BG2 yet. But as far as introductions go, the introduction of Irenicus and Imoen and dungeon crawl to the Promenade are head in shoulders above our brief jaunt through hell and all the vague Absolute stuff.
But I'm someone who still enjoys going back the BG2 so maybe my opinion is colored by years of hind-sight. I can't be really sure what my first impression of BG2's intro was, except that it was heady and made me want to rush through the game to save a friend from being tortured (I was a more naive gamer then). I'll have a better impression of BG3 when, or if, they make the tadpole into a more effective ticking clock.
Literally ticking clocks are actually quite rare as they can be very limiting in how a game is played. Neither BG1 nor BG2 had a ticking clock, even though they had day/night passage of time. And we already know that the BG3 tadpole is quiescent to some degree.
What all 3 games share is an underlying sense of peril ( Sarevok, Irenicus/Bodhi, Tadpole/Absolute ) that serves as a narrative hook. However, you can easily "bunk off" in all 3 games to investigate everything that is not gated behind story arcs. Usually, in a first playthrough, I will largely follow the central plot with few diversions; but you can easily justify a slower pace as needing to gain the additional power to succeed.
To me, the story elements so far look promising and potentially complex; but I will withold judgement, as many games start with interesting scene-setting, only to taper off into a bland finale.
