they look a bit ugly in screenshots, don't know in game.
if I'm not wrong the spheres used are of 16 edges, this is enough usually with the ship meshes to have a sphere looking as.. a sphere:doubt: , but used as shockwaves they look a bit low poly.
this could partially depend by smooth shadings not used (if it is this the case), but I think that the major part of the problem (if we don't want extradetailed spheres) depend by the contrast between the edges of the shockwaves and the dark background.
if only we could have the edges fading or alternatively a fading glow surrounding the sphere, this would reduce a lot the contrast and the sphere should look little better.
This problem is similar to when you add planets as ingame meshes: without a way to simulate the atmosphere fading around edges, the edges look too defined and the result is horrible