If you think Inception had a complicated plot, this movie isn't for you. Really. There's charts with loops on the Internet which show the plot and what's happening when. You'll probably need to watch this movie at least twice.
It's very, very good.
Visually sumptuous, but the pacing is painfully slow, and the narrative is simply boring. Berger's performance, the Bavarian locales, and Visconti's apparent identification with his subject are worth the significant investment of time, though.