I'm playing through the campaign at the moment. I've been really out of touch with the game, i've not played in ages, but I found the missions were criminally easy on normal. But that's probably that i'm not a bad player, was platinum back in S1 and WoL was the first time i'd really played the starcraft series.
Overall I think it's fun, i'm enjoying the story line and I quite like that you collect a mishmash of characters that each have an interesting dialogue as part of the story. I agree with some of the units coming in too late and the earlier levels are really a case of "just give me some damn mutas/infestors/other zerg unit so I can pwn this level quickly and move on".
As a quick question, I sided with Tosh in my first play through of the WoL campaign (I think I went Tosh, Nova, Tosh as I went through on normal, hard and then Brutal) and thenSpoilerPotential Spoiler for the storylineSpoilerNova is one who captured Jim during the early campaign levels. Is this different if you sided with Nova in the earlier campaign?