The three main groups of Jews in Yemen are Baladi, Shami and Darde'i.
Baladi Jews are what Lithuanian (and nusach Ashkenaz) Jews are relative to chassidic Jews in Ashkenaz. Baladim are actually a result of a compromise of the Maharitz to break the deadlock between the followers of Rambam and followers of the Ari z'l (known as Shamim since an Ari z'l follower from Shami, Syria brought the Ari z'l's teachings to Yemen). This can be seen in the Baladi adopting of the Zoharic passage of Berikh Shemai recited by Baladim AFTER removing the sefer Torah from its ark. Previous to the Maharitz, Baladim followed Rambam and therefore did NOT recite Berikh Shemai. Darde'im are Rambam holdouts who did NOT accept the Maharitz's compromise. They do not recite Berikh Shemai. They go further and REJECT the Zohar! Halakhically it is problematic to count them in prayer quorems, eat their slaughtered meets, use them as witnesses, since they reject part of the Torah that is accepted by the rest of the Jewish people. In mentality, they are anti-mystical, Baladim are not anti-mystical, but they many times side-step mysticism, while Shamim embrace mysticism, though probably less than Sefaradim, since Shamim have been shaped by the rationalism of Rambam. Halakhically, Shamim are very similar to Sefaradim, though on some issues of the Beith Yosef, they go with the legal decision of the Rambam. Chalita (boiling raw meat in a special way, instead of salting it) may be a good example of Shamim going like Rambam instead of Beith Yosef.
There are two main pronounciations of Yemenite Hebrew, considered to be the most accurate since all letters have a distinct sound except for samekh & seen.
The Sana'ani pronounciation (used by the majority) has been indirectly critiqued by R. Sa'adia Gaon since it contains a jimmel & guf, which he rules is incorrect. R. Mazuz demonstrates this through the Jerban (Tunisia) Jewish dialect's use of gimmel & quf, SWITCHING to jimmel & guf when talking with Gentiles in the Gentile dialect of Jerba. The Shar'abi pronounciation of Yemen is more accurate & similar to the Babylonian dialect since they both use a gimmel and quf, instead of jimmel and guf.
Enough for now.