Serum has one of the best interfaces I have used in a soft synth. It is very easy to navigate and inspiring in that it encourages experimentation with sound and patch creation esp once you get into making custom wavetables. It is also a good synth to learn if you are new to synthesis due to the inteligent GUI. I had the opportunity to use it for a while and I created some patches for it which are mostly pads with some custom imported wavetables.
As for sound, Serum is very clean and 'digital' sounding if a little clinical. This might fit modern and harder electronic styles but is maybe not the ideal choice for softer and warmer more organic electronica or the type that looks to vintage sounds for its basis like classic berlin school. What it does do well though is create sounds that cut through the mix. If you mostly have analog hardware synths or software vintage emulations then serum can be a nice addition for that clean sound to add an extra dimension. Its effects engine can also be used seperately so this is a bonus in that you can chain it with another synth. Its effects section is versitile and again super easy to use. If you want that pure vintage electronica sound then look elsewhere but as a modern clean sounding synth engine it is one of the best at the time of writing.
*** RECOMMENDED FOR MODERN ELECTRONICA ***