There must be option to maximize cloud render preview! Now you must resize window to whole screeen to see it...
There must be option to start render in background and continue to work. Setup should include number of iterations, resolution, and CPU limits (number of cores used for render or something similar). Also there must be render option for animations.
Now there is no material editor. All you can do is customize something that is already made. Also material editor need to have better preview in real time of material you are making, not this small 10x10px....