I actually prefer the new UI. The advantage of being able to plot enemy ships and alter TDC settings whilst at the periscope is great. Minor course changes can be set via the turn to where I'm looking command.
The only thing the new UI is really missing is the ability to return to course, but I'm sure this will be added at some point.
I think it would be a step backward if the UI returns to SH3 or 4. Maybe we could compromise and have the current setup with 'real' TDC controls down the left?
Its a shame that I am in the process of returning my copy. Not because of the game - which I actually like lots, but because the DRM prevents me from playing