Useless in Vanilla, but her mechanic was made useful in Rise and Fall. What a big difference these changes can make.
Leader Ability: Monty Catherine's Flying Circus. Gains an extra level of Diplomatic Visibility against every Civ she's met. Gains +1 Spy Capacity at Castles, plus a free Spy. All Spies start with one Promotion. Catherine is also able to secretly buff Ze Fwench Civ in every patch and expansion. Look out Aztec - 5 more expansions and 72 patches, and she'll be A-Tier
You start with a +3 combat bonus that gets doubled to +6 once you put in a listening post, since nobody can do that before you. Get to Printing, and well, that's a lot of power. Of course, this doesn't help you with barbs or city states but is great for rushing. France pretty much has to play the start aggressive. With the AI being very aggressive early even on King+, that +3 really helps.
I find the first spy mission is probably safest with listening post, and the maybe messing with a CS.
Civ Ability: Grand Tour. +20% Production towards Medieval, Renaissance, and Industrial Era Wonders. Double Tourism from all Wonders.
Bonus towards most of the late game hitters which is nice. It's no China, but it's still good.
Unique Unit: Garde Imperiale. Basically a Bizzarro Red Coat. Unique Industrial Era Melee Unit (unlocks at Military Science, upgrades to Mechanized Infantry). Melee Strength 65, Movement 2, Produciton 340, Maintenance 5. +10 Combat Strength fighting on your Capital's Continent. Generates Great General Points from kills.
Yea, basically this is the opposite of a redcoat but unlike the Redcoat, you can't get them for "free" which sucks but they are still good for emergency defense. Not very useful overall.
Unique Infrastructure: Chateau. Unique Improvement that unlocks at Humanism (one builder charge). Must be built adjacent to a River. Provides +2 Culture, +1 Appeal, +2 Culture if adjacent to a Wonder, and +1 Gold if next to a Luxury Resource.
Because it's stuck to a river, it's not in a good spot since you want to reserve river spots for other more useful things. You may want to spam these in a random tundra or otherwise useless spots to get tourism with flight. The yields themselves are rather poor. But at least it's more useful than the mission.
Leader Agenda: Black Queen. Gains as many spies and as much diplomatic visibility as possible. Dislikes Civilizations that ignore espionage.
She cares about diplomatic visibility, not always spies. You'll be friends with her if you are Mongolia, and France is also the civ you don't want to mess with since they negate your ability passively anyways. This actually tried to be a thing:
https://en.wikipedia.org/wiki/Franco-Mongol_alliance
France is probably of an average power. Much better than most people give them credit for because they underrate early game bonuses and overrate late game ones.
Sigh.
@Archon_Wing has started a RnF Civ Tier List thread. Gathering Storm comes out in a few months. And we've done all the cool Civs. Is anyone reading these anymore...? Maybe we do Russia next week, and then do Brazil and Australia as a combined Grand Finale??
Well, I'm not going to like, not play civ, until the expansion (that's crazy), so yea I'll still be playing games of course. And Australia can't just be left out!
Really t'd me off, and it blew one part of my strategy. I still built some apostles, but Japan converted so many civs, that I had trouble finding enemy apostles to kill mine. As Japan won't kill apostles with their religion. My strategy for Mont St. Michel was kind of a bust. 
