The Ibn Ezra (Koheles 5) criticizes the Piyutim of the Kalir.*
He has four main complaints against them.
1) Most of them are Chidos (riddles) & Mosholim (parables)
2) Instead of Loshon Hakodesh he mixes in Loshon Hatalmud
3) He invents words & uses improper Dikduk (poetic license)
4) They are based on Medroshos & Agodos instead of Pshat
The Teshuvas Maharashdam (O..Ch 35) claims,
The Sephardic Paytonim have a simpler and easier
language. Everybody can understand the Piyut, whereas the
Ashkenazi Paytonim use difficult words and even the
Shatz (Chazzan) doesn't understand what he is saying.
He recommends Ashkenazim to switch to Nusach Sefard,
which is a superior Nusach. He claims "Al Titosh Toras
Imecha is only applicable when there is a small Issur involved
and not for changing a Nusach Hatefilah.
The Chasam Sofer (Hagohos O.Ch.68) writes that "the Mahrashdam
wasn't aware of the Magen Avraham (68) who writes. you are
not allowed to change the Nusach Hatefilah because
there are 12 gates in heaven, one for each Shevet. Each one
has his own Minhag. The Yerushalmi says, they are all equal
you should not change from the Minhag of your fathers."
Had the Maharshdam been aware of this M.A., he wouldn't
have written what he wrote".
* Shabbos Zachor
Piyut of the Kalir starts with
אָץ קוֹצֵץ בֶּן קוֹצֵץ / קְצוּצַי לְקַצֵּץ
בְּדִבּוּר מְפוֹצֵץ / רְצוּצַי לְרוצץ
לֵץ בְּבוֹאוֹ לְלוֹצֵץ /פֻּלַּץ וְנִתְלוֹצֵץ
כְּעָץ מְחַצְּצִים לְחַצֵּץ / כְּנֵץ עַל יוֹנָה לְנַצֵּץ
אָץ- He rushed
קוֹצֵץ בֶּן קוֹצֵץ - The clipper* son of the clipper (רשע בן רשע)
קְצוּצַי לְקַצֵּץ - The clipped to clip (Bnei Yisroel - the harmed to harm)
בְּדִבּוּר מְפוֹצֵץ - with slander
רְצוּצַי לְרוֹצֵץ - The crushed to crush (Bnei Yisroel)
לֵץ בְּבוֹאוֹ לְלוֹצֵץ - When the רשע came to do evil
פֻּלַּץ וְנִתְלוֹצֵץ - The evil turned back against him
כְּעָץ **מְחַצְּצִים לְחַצֵּץ - for wanting to shoot arrows on Bnei Yisroel
כְּנֵץ עַל יוֹנָה לְנַצֵּץ - and wanting to devour like a hawk the dove
*בדרך צחות barber
על פי שירת דבורה**