Is immersing the right word, to describe it? Its pretty immersing and it's good that it doesn't force you to rush after Irenicus. You can do it all at your own pace.
I actually always saw it as a weak point - I think the only "big" picture issue I can indentify with BG2 (there are smaller things which I think aren't as good as they could be, but I don't think they hurt the overall experience). This lack of urgency and distraction goes against the narrative and your character motivation. From narrative perspecitve the side jobs are only there to get money to pay for saving Imoen, and it doesn't make sense for the the Bhaal Spawn to be a freelance adventurer for longer then he needs - no matter if his motivation is care for Imoen or revenge. It makes even less sense if you save up sidequests for after the underdark.
I thought Witcher3 got around that problem nicely, but giving player excuses to not progress the story "Hey, Ciri is safe for now, and if you rescue her the hell will break loose. So you know, make sure you are prepared for it first wink, wink".
