Jeanne D'arc(ruler)???

She is not bad if you can use it properly. She is a full support tank servant and i think she have same role with Mash.

Well actually she is my waifu too (also with her Alter)... But her role is for defensive and supporting, and i already have Mashu with Lv, Skill, Atk, Hp all Maxed... +my strategy is about attack and attack, besides i can borrow my Friend's Jeanne with maxed stats... So— i not roll for her

But if you want her so badly for waifu reasons, then go for her

She is an incredible tank due to her Ruler class and her having the highest HP stat in the game. However, in an offensive oriented game, her performance is often trivialised.

Her NP provides a nice heal and def buff, but also grants a 1-turn invincibility to block incoming NPs. However, it stuns her during and after the turn she uses her NP, preventing her from forming chains. This demerit is removed after she receives her interlude, which makes her NP spamming and tanking potential even better.

She's a very good staller and can perform well in arts teams and against servant bosses, the latter commonly found in future challenge quests. She's a great investment as a future unit and will be relevant in harder content.

Jeanne was my first five star servant. I think it is worth rolling for her, especially if you like her character. Her niche is a bit different than Mash’s; Mash provides general, all-purpose survivability whereas Jeanne’s role is to ensure that her team consistently survives enemy NPs. Jeanne offers one-turn of teamwide invulnerability (plus a modest defense buff and some healing) via her NP, which gives her greater potential to spam her invulnerability buff than David or Tristan, whose teamwide dodge comes from their skills. Jeanne also has a skill that has a chance to stun an enemy servant. So, if you use the Chaldea Combat Uniform Mystic Code and have David/Tristan on your team, you have two stuns and two teamwide dodges at your disposal, so you have great survivability of boss NPs.

The downside to Jeanne is her very low attack for a five stars, her other two skills are mediocre, andher NP stuns herself. However, Jeanne was never meant to be an offensive servant in the first place — she keeps your damage dealers alive so they can kill the boss — and her interlude (not yet available in NA) actually adds a debuff removal, so her NP no longer stuns herself AND it clears debuffs from the rest of your team.

Personally, I don’t think of any 5 star servant as being “bad”
Some servants just get the job better but that doesn’t really make other servants inferior. My favorite servant that I’ve used since Orleans is Altria. There are more than a few sabers that outclass her but I really have no interest in using them.

Playing the game with your favorite servants makes things more difficult but I personally feel like you have a lot more fun doing it that way

She is very good its just her uses are also very niche - she is an anti servant tank and at that role she is the best in the game. So that being the case her usefulness rises and falls a lot based on how many strong servant bosses are currently out there following the JP tier list at her height she was just behind Waver and Merlin on the list while now shes way down in the above average section shes never "bad" though, at least for bosses her real problem is most of the game is farming not bosses and for that she's pretty useless.

Very Niche Servant that excels in her role. Which is stalling out harder content/Challenge quests. She is basically only for the hardcore future content FGO will be getting a year and a half from now.
Reason being her skills only work on servants and her NP basically negates the enemy NP and helps in stall teams. Or you can plugsuit her with a Scope or NP buffs/Imaginary Around.
Not useful for anything else unfortunately as she is just a damage sponge outside of those specific quests. Low damage and high HP plus ruler class having no advantage.

It's your waifu, roll for her. If she's useful or not doesn't matter. Always put waifu as top priority.