I'll go out on a limb and say that Ljudet Innan and Storm Corrosion are two of the best songs that both Mikael/SW has done (in all their projects).
I think I've said it before, but if I were to rank all of the albums I've heard from both Mikael and Steven Wilson together, the top three would be Blackwater Park, Fear Of A Blank Planet, then Storm Corrosion.
It's funny, because I went into the album when it came out not expecting to like it at all. I guess the two reasons I like it so much are A) how much atmosphere it has and how it covers a bunch of different moods instead of sticking with one throughout, and B) unlike a lot of other ambient records, it's still got a lot of melody and memorable musical parts to it.