I enjoyed the change of pace back in BG2 when the romance music came on and the companion would shift focus from adventuring to personal relationships. It was like take a break time.
On subsequent playthroughs however, the dialogue tree became more and more apparent and it lost its charm. So, if the relationship is more systematically robust with highs and lows, challenges and comforts, I'll like it a lot.
I ticked Karlach with initial MC, but can't really say until play.
