So no, not a drop in replacement. But not a difficult transition either.
This page explains how Polars differs from Pandas.
https://pola-rs.github.io/polars-book/user-guide/coming_from...
df.with_columns( pl.when(pl.col("c") == 2) .then(pl.col("b")) .otherwise(pl.col("a")).alias("a") )
Seeing the multiple nested pl calls within a single expression just feels odd to me. It's definitely reminiscent of Dplyr but in a much less elegant way.
Another caveat for me is at multiple times in my workflow I drop into R for plots and rpy2 can convert pandas dataframes into equivalent R atomics. With Polars it would be just an additional step of converting to pandas df but just something I need to consider. That said, I've disliked the Pandas syntax for so long that the mental overhead might be well worth it.