It's fast and does editing on the fly. Had a few bugs on the newest version which they worked to get fixed. Excited to see this continue.
The output is really fast even for 4K. It's cloud based so no more taking up resources on the computer when it comes to the extra processing. Also export can be done in the background or just left to be done after you close the window so it gets processed regardless of whether you turned off the computer.
They seem open to and accepting of suggestions and really responsive so if they keep that up they will grow quickly be a big competitor for others out there.

Now for the only negative I can think of:
Biggest Con would be they do need a mobile version because when on the road and I need to get something done I do it from my phone. Even if they just migrate the earlier version to a phone app that would work for me.