I toured the IH plant when they were building the 5088.  Most interesting part for me was a machine that actually turned the frame and transmission upside down before welding.  Tour guide explained to me after I asked "Why" that they had lots of welders that were good at horizontal down, very few that could weld vertical or horizontal up.

I can relate to that, got almost good at horizontal down, had lots of trouble with vertical up and horizontal up.  A farmer in our area, now deceased, had worked in shipyards during WW2 welding horizontal up inside ship hulls.He would actually hang something up in the area to weld it anytime he got a chance.

A couple of things I thought I would practice until I could do them well, spray painting and welding all positions.  My welds looked a lot like yours, but they almost always held due to getting good penetration.  I did one excellent job extending a loader frame that I still own, but actually spent more time on surface prep than welding.  Might be some of the problem with your welds, I often was trying to get back to the field quickly, and didn't prep surface as well as I knew how, but got the job done so it held.  I finally got one perfect spray paint job on a fuel tank and crossover tank matching my FIL's pickup color.  Most other paint jobs were fair, but had at least one run where I tried to get paint too thick. 

Some skills, for some people, are just very hard to learn. 

Your welds aren't that bad, but I would wonder if you had penetration.  Keep practicing. 

Added later:  My welding improved a lot when I sold my Lincoln buzz box and bought a Lincoln ac/dc buzz box.  I weld now with DC mostly, and 7018 rods.  A good welder man can weld with anything, but for a poor welder like me better quality equipment did helped a lot.