This will mostly likely never get addressed, but hey... No harm in voicing it.

The server browser in this game, is inexcusably bad.
Jump in a game from the late 90's i.e: Quake or UT and have a look at theirs. They perfected them way back then, why are we going backwards on this?

We need some REAL filters for the browser for a start, ones that are persistent as well.
Adding a server to favorites in this game is a joke.
There should also be a way to add a server while IN said server.

Choosing to filter servers with friends on them returns a handful of results with no indication of which friends is in which server.
You have the Steam platform at your fingertips, and really, you failed to use it properly at all.

Finally (for now) the design of the server.
Once you open a server browser, you should have complete control while in that one window. Albeit by adding context menus to right click or just easily identifiable buttons.
But if I want to search favorites, I have to click back while looking at my server list, then click source, and go favorites, then search again.
Or if I want to see friends, I have to do the aforementioned process.

This may seem like a petty or trivial problem, but really... It's not.
So many games these days are coming out with server browsers that aren't functional, and this one is quite possibly the most annoying one to use since Crysis 2... And that should be saying a lot.