Amber is a setting I adore, I loved the books. But the system...wow. Do you really need to trust the GM! I played for about a year with a GM who, well, let's be honest. If he didn't want you to succeed, you weren't going to, no matter what your Attributes were. A lot of times, the only time Attributes seemed to matter was in PVP, which I'm not a huge fan of.
And whatever Attribute I was best at, seemed to be trivialized more often than not. His common complaint was that I "just wanted to win" all the time. Which confused me, if I'm First Ranked in, say, Warfare, I'm an amazing warrior who can overcome anyone who decides to face me in a fair fight. A big factor in the game was trying to switch the combat from an Attribute you were bad at, to one you were good at. But every time someone came at me with a sword, this ensued:
"So what is the guy doing?" "Oh you know, feeling out your defenses, parrying, that sort of thing." "I'm better than him, right?" "Oh yeah, by a lot." "I'll slip an attack through his guard to let him realize that (hoping to get the guy to surrender)." "Ugh, this again? Why won't you realize you can't just win right away? This is going to take time!" "Ok, so I have to slowly wear down his defences?" "Yes, which makes this an Endurance test." "Wait, what? He came at me using Warfare, why is it Endurance now?" "Because you couldn't defeat his defenses right away." "So how to I change it back to Warfare?" "I don't know, tell me what you're doing." "Describes a shield bash to throw the enemy off balance." "Uh, that sounds like Strength. What's your Strength again?"
And so on. Any time I'd have an advantage and try to press it, he'd suddenly want to change the combat to something else, and then force me to figure out how to get the advantage back again. We'd spend a lot of time on this, while other characters would go "Uh, I touch the guy so I can overpower him with my Psyche." "Ok, he falls down."
I finally decided that I really needed dice in my life, so I can actually "see" how good I was, so I never touched the game again. Relating the story now though, I don't know if I can completely blame the GM or not; he often seemed annoyed that I knew more about the setting's lore than he did, having read all the books multiple times, and even owning the Illustrated Encyclopedia (when I had a hard time getting anyone else to even look at my paperback copy of Nine Princes in Amber)- maybe he felt threatened, or thought I was trying to exert undue influence over the narrative?
Either way, since the system has no real way to break up a dispute when the players are at loggerheads other than a loosely defined system of "good stuff/bad stuff" (ie, unspent points at character creation gave you a loose sort of karma), I'm left to conclude that whether or not it's a great game depends on the group.