Pluspunten
For the most part, the Paul Scherrer Institute is a fair bit relaxed in comparison to ETH or other university research institutes. Far less people spending crazy hours in the lab as most people treat it (and expectation is) as a regular 9-5 or 8-4 working environment. Though this doesn't apply to beamtime hours ...
Speaking of beamtime - for chemists, biologists, material scientists, you have a very close relationship with very exclusive beamtime facilities and it's rather easy to gain access to extra hours in between experiments (or if experiments fall through) should you need. This is advantage is highly unusual at most other university institutions.
Minpunten
Trying not to get my personal experience too wrapped up here.
As usual in many institutions, there is a lot of politics which can make for challenging or unpleasant situations at times. Also, the campus is far from any city, and there isn't much life on or off the campus as many of the scientists are more family oriented. At times there are initiatives to build up an engaging social environment and more of a 'life' for scientists on campus, but covid hit this pretty hard. Hope it builds back up again. Overall, the culture feels a bit slow and conservative.