I like musicals and don't much like opera, but for me it's in large part about vocal style -- in particular I'm not keen on operatic sopranos and the music that tends to be written to showcase them. (In musicals the soprano solos are likely to be my least favourite bits, too.) I think there's some sort of musical continuum going on here but I'm not sure where the boundaries lie. Curiously, I prefer sung-through musicals (which I suppose are more like opera) to songs+speech; I sometimes find the suspension of disbelief harder with the "intermittently bursting into song" style than with "it's all just singing".