Few things going on there. To me it looks like your wire speed was too slow. The welds look to have stuck but it's interrupted. The trouble is that on these thin panels you'll struggle to hold a bead. Have a look at 'pulse' welding, it might help improve the appearance of your welds in future. Some machines can do it for you but you can do it manually (albeit much slower).
The 2nd thing is that personally, I wouldn't have just done a flitch repair. You have a ruddy great hole behind the shock mount so I'd have opted to replace the whole inner wing. More expensive but you'll be able to better sort out the problems that lurk behind.
And last one - flap disk/linishing wheels are great for tidying up welds and for the areas you can't get to, get yourself a finger sander and a handful of belts to go with it.
