Your welding looks fine, but you could have given the finished job a more professional look if you had fully welded the gusset plates going in the opposite direction running them all the way into the corner. Then when you put down the bottom fillets you would have sealed the ends up nicely. Just my opinion, but I think if it had been fully welded it would have given it a more overall pleasing look.
We welders are often a critical bunch of folk, but I think that just spurs us on to produce top class welding. As opposed to other engineering disciplines, which require skill, I see welding as an art. Others may disagree, especially those in other engineering disciplines.