This lake is absolutely beautiful and sometimes gets a bit forgotten due to the "fame" of the Seealpsee. Howevery, I am sure you will love it and you can even visit Samtisersee on the way or Saxerlücke.
I recommend to start from Brülisau, where you can park your car or of course also reach it with public transport. The lake is also great to have swim and refresh yourself after a long hike.
The trail itself to the lake is not really difficult. But it will require some fitness (especially the first ascent from Brulisau. You will pass the lovely Sämtisersee where it is worth to stop or also straight continue. Many people come only here to do some barbecue and enjoy the views.
Then you can continue the hike towards the Fälensee which is not as steep anymore and actually super scenic and pleasurable. I can truly recommend to also stay overnight at Bollenwees the hotel inn at the lake. but of course you can do all hike in one day.
However, I believe the most beautiful reflections you'll get in the morning or late afternoon.
Photography tips: The viewpoint from above is right behind the hotel bollenwees where you can just follow the trail until you find the frame you like. And the other photography spot is when you walk down to the shore and get the crazy reflections in frame