Initial prints on Sumpod 3d Printer

My Sumpod 3d printer arrived a while ago but it has taken me this long to paint (sand, paint again, sand again, …) the MDF. I finished most of the build last weekend. Since then, I’ve been attempting to calibrate it in any spare moment. After initial problems with the extruder and with the X axis belt being too loose, it does feel like I’m making progress. This print started quite well:

and the bottom layer looks pretty good:

but quality of the sides varies quite a bit:

and the top looks dreadful:

so there is definitely some calibration to do.