Ver 10 has becomes less useful for me because it appears that so many of the pre-defined commands appear to have been dropped from the UI. Notably, the list of "File Commands" that was in the file menu (the one that let you split files, join files, create links, copy source code, etc.)
It seems like with version 10, there has been an emphasis on stripping out the lesser used features from the UI. There were lots of commands I didn't use often, but they were huge timesavers when I a did need them.
In version 9, I had the option of either doing something manually which might take 10 or 15 minutes, or use the DO Command that would take an instant. In version 10 I have the option of doing something manually (10 or 15 minutes) or spending half an hour or longer researching how to create a command in DO for it.
But perhaps I'm overlooking where these commands have been moved to.