Travel speed towards the end of the weld in the first pic looks like it was a bit erratic and judging by the spatter on the starts either the wire feed/volts aren't quite right or the earth connection could be better. The second weld looks great if perhaps a little cold.
Only thing I could add, is to try not to have stop/starts too close to the corners as it will likely be the corners where any cracks could start, also to overlap you stop/starts a little more. Ie in the top pic, where you picked up the vert weld from, you could have picked up from right in the crater of the hori vert fillet then weld around the radius of the box and down.
Other than that though, id say youve pretty much cracked it, yes.