First, some great usability enhancements within the Modern UI, especially in this latest round of updates in 4.7 – exciting things are happening here so keep up the good work! 
That said, my company has one major concern…
Internally, we created a visualizer (i.e., a “blue” KNIME node) built upon the Java 2D API that also leverages the “highlighting” feature within KNIME – we use this frequently to display models and trace back visual anomalies to our input tables.
In trying out the Modern UI, we noticed that our custom visualizer did not have a “magnifying glass” option to view the plot whatsoever – this seems to be the case for all non-JavaScript visualizers (e.g., the “Local (Swing)” category of nodes). It also appears that the “highlighting” feature is not accessible within the tables (i.e., you cannot see what you highlighted in the table views). We noted that you can still use the “HiLite Row Splitter” node to figure out what was highlighted so the information is still stored, but there seems to be no way to make and track selections within the tables anymore.
This raises a few questions:
- Will non-JavaScript visualizers ever be viewable within the Modern UI? (If not, this would be a significantly blow to our ability to use KNIME going forward.)
- Will highlighting ever be accessible within the tables views of the Modern UI? (This was one of the biggest draws of KNIME as it allowed you to trace the evolution of your analysis on specific points of data.)
- At what point will the Modern UI become the “only” option? (I noticed a team member stated, “someday in the future the current user interface will not be maintained anymore” so it would be nice to have general timeline for this transition.)
Aside from this, I did note one other technical issue:
- If the user has a 4K monitor and is also using the Linux version of KNIME, then the Modern UI does not “extend” across the entire screen. That is to say, only a quarter of the window displays the UI while the rest of the screen is “greyed out”. Looking back in forum posts, it seems a similar issue of 4K + Linux has come up before yet with no resolution (see Node-icons and dialogs with HiDPI (linux) - KNIME Analytics Platform - KNIME Community Forum).
Again, keep up the good work! 