Ranked in these QuestionsQuestion Ranking
Pros
Pro Lightweight
Needs only Python and mpmath library.
Cons
Con Quite basic
Con Python interface is clunky
If you're using CAS within another program, it's great that SymPy is written in Python.
But most of the time you're just trying to do some math, and having to declare all your variables and write equations in obscure ways so they fit Python syntax can be annoying.