From the restfulness point of view, not so much. I am not a light sleeper but the train was noisy and jerky and the bed narrow with your body perpendicular to the direction of travel so it kinda sucked. Not really a "hotel on wheels" from that point of view.
There was no security to deal with, however on the train from Budapest to Vienna that I took the day prior was searched by armed police. Perhaps Vienna to Venice is a lesser destination for people the authorities want to screen out.
I don't have climate anxiety and I fly around a ton. On a 3-week euro tour where money wasn't really an object, it's totally worth it for the experience to do the night train. If time or money mattered then this would not have been the way I'd go.
As an aside, I've seen the train at best "break even" on time and experience. The Acella between Boston and NYC, and the Eurostar between Paris and London take longer than flying, even when factoring in the travel to the airport. If you want the uninterrupted train time to read or snooze then maybe it comes out ahead. Price wise the train is way less practical but with the company paying for my travel that's not an issue.
As Americans it's customary for us to genuflect to Europe for it's enlightened train connectivity and there are places where that works very well (eg Paris to Stroudsburg) but for cross-country travel it's not really that great.