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.
I prefer BG1's intruduction.
BG2's assumed that you've travelled with this predefined partt (Imoen, Jaheira, Minsc, Khalid and Dynaheir) in BG1. Even if it happened that these npcs died in your BG1 playthrough, which is pretty immersion breaking right from the start, imo. And then they made Imoen a Bhaalspawn, never explaining why her essence didn't return to the throne upon death as with other Bhaalspawn characters, including the main one.
"Hello Xzar...I seem to remember you being dead..." ; "Nevermind that!...have a quest!" There were some things in Baldur's Gate you just had to roll with, the Heisenberg world-state of your BG1 narrative was one of those things :p but I get it.
I agree with you that making Imoen a secret child of Bhaal feels like a hasty story choice, but as far as death goes in D&D in general I tend to already be rolling my eyes, nobody really died, they're just
mostly dead...except when you're gibbed of course.
And Imoen's revelation does nothing to detract from the introduction for me, I like BG:1's intro too but it doesn't get me as invested in the plot as the introduction in BG2 does.
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.
Ticking clocks don't need to be literal to spur the narrative along, video games are interesting because they allow for them to actually be literal, but in most stories they serve as a way of adding tension and drama to every choice the character makes. If the tadpole in BG:3 was turned into a literal ticking clock, that would be fantastic but I would enjoy just as much a more clear introduction of their danger, as it is we have a scary thing in our head, everyone tell us how we need to be rushing to find a cure, but then everything else that happens in the first Act undercuts that as you dither around.
I was comparing introductions between BG2 and BG3, I was frustrated (in a good way) by the hurdles placed before me at the end of BG2's intro, while for BG3 I question the motivation of my character and the party.
