Zaydism is a batil sect, based on false attribution to Imam Zayd (rh). Their theology is Jahmite-Mu'tazili-like, an absolute disaster and they have committed many crimes in Yemen (not just the Jarudi-Zaydi Houthis, of which many - especially their leaders - have turned Rafidi Twelvers). There is an Ex-Zaydi brother on Twitter, over the years he has exposed their sect to the max. In Arabic, many Shafi'i Yemeni scholars have refuted Zaydism and their false claims to the Ahlul-Bayt.
Yes, compared to Twelver Imamite Rafidism (due its extreme paganism and savagery), Zaydism looks super orthodox (but common, it's not difficult, as Twelver Imamism is so repulsive for people with intellect, of course every person with half a brain will eventually leave it) and Shaytan fools some by claiming that it is 'the middle ground' (between Sunnism and Rafidism), but trust me it is not.
The only problem is that most material, almost 100% really, that deals with Zaydism and refutation of its falsehood is available in Arabic, I personally have benefited a lot from the Ex-Zaydi (now Sunni) brother on Twitter that I've mentioned already, here a link to his account:
https://twitter.com/asas12367?lang=enHaving said that: As Sunnis we should embrace Twelver Shias who become Zaydis, it's better for them and for us (Houthis are from the most extreme sub-sect of Zaydism, the Jarudis, they are semi-Rafidis and should be fought and will be crushed by the Sunni Yemeni nation in due time, Inshaallah). I've met Zaydis and despite all our differences, they are definitely the type of Shia (many of them don't even like the term Shia and prefer Muslim and Zaydi only!) that can peacefully co-exist with us, many of them have converted to Sunnism in the last few decades in northern Yemen (where some of my relatives live), among them major Sunni figures like al-Shawkani and Shaykh Muqbil.