I expected this to provide a certain "cool" factor and to help in ensuring better extractions, owing to the fact that you can directly observe the evenness of extraction from the bottom of the basket. It certainly does both of these things. What I was not at all expecting was how much better the coffee would actually taste and look!
This may be due to the fact that my old Silvia portafilter has become rather dirty with bitter coffee residue. However, the first thing I noticed was all the extra crema. Lots more; maybe 2x as much. And the colour -- much of the crema is way darker than before. There are more different shades of crema.
The best thing of all though is the taste. Upon drinking my first cup (a latte), I immediately noticed that a certain bitter taste that I'd been living with for years - and which I assumed was just part of the coffee I was using (which I roast myself) - was gone.
I guess that having the freshly-extracted coffee run over the dirty surface of my old portafilter had been killing some of the crema and imparting a bitter taste.
I can't really say enough about this. I just wish I'd bought one years ago.