Mann Overboard - Wishing Mephisto were a better novel

Klaus Mann's 1936 novel, Mephisto, set among the "intelligentsia" of Nazi Germany, is important, brave, historic, controversial and, despite all that, I wish it were, well, better. How can you not give K Mann credit for overcoming the ridiculous expectations of famous father Thomas and for standing up to his horrific bro-in-law, telling truth to power in Nazi Germany from a position of maybe not so safe exile - it's a great thing that he wrote this novel, that he lived to see it publish, and, despite all the controversy - a complicated lawsuit from his ex bro-in-law who claimed the novel defamed him (ha! - imagine that, defaming a Nazi sympathizer and collaborator) - to go on with his difficult, short life and to continue writing. But much of this I learned from the short preface and the jacket copy on the edition I'm reading. The novel itself is really pretty dull and drab - long conversations amongst various theater folk, very gossipy, probably much more interesting at the time of publication when readers caught all of the allusions and references (the novel is very much a roman a clef) but today it's hard to follow, hard to engage. K Mann is telling the story of what I learned is his ex bro in law, an aspiring actor w/ stage name Hendrik Hofgen (I think?) who collaborated w/ the Nazis to advance his career - bad decision! - and anyone whose read Blood of the Walsungs or Disorder and Early Sorrow, T Mann's account of his family including his children, will get that K Mann had a weirdly close relationship w/ sister Erica (?) who married the actor represented by HH - so there's all kinds of autobiographical strains in Mephisto - if only Mann could bring these tensions to life. I will give the novel more time, but find it to this point stale, flat, unprofitable.