I played them both a few days ago. 'Fragile' was way too dark... I put my monitor into ultra bright mode to play gish since it's so dark and atmospheric, but even this level barely shows up as a trace. Also there was tremendous slowdown at the beginning which is unusual for this computer.
'Avalanche' was a nice level but a little too short and simple, and lacking any nice details that make a level come to life.
These are good for first levels, though. It seems like you're just getting to grips with the editor like me.