Okay, i got the Friesland two day's ago and this is what i can tell about her:
She is a hard to play ship i have to agree with that. To really use her at her full strenght investing in concealment/rof and AA is a must. I have some nice games in her mostly around 130k damg. Remeber she is a team ship, so use het in a supporting way. Going alone always ends up in sinking or losing the game. Place smoke in smart places and put here in good positions she can really f**k up bb's dd's and even ca's (without radar ofc).
If you really want her to be at her most powerfull? Go in a division and let the otherguy use a radar cruiser to support you.
I also wrote that when subs come she wil get a new weapon (i think those missles against subs) she is a sub/dd hunter trough.
Also going in a division with three friesland.. You can troll so much..
This is my opinion.