Good or good enough for a particular need or purpose: a satisfactory outcome/result/solution. a satisfactory performance/progress.
The phrase "far from satisfactory" is correct and usable in written English. You can use it to describe something that is not satisfactory or not satisfactory enough. Example: The results of the experiment were far from satisfactory.
``Satisfactory'' is only negative in a context in which there is a range of possible grades (used broadly, not just to mean in a school) and ``satisfactory'' is commonly understood to be not very good. Literally, ``satisfactory'' means satisfying the requirements in question.
If something's satisfactory it's okay — acceptable, but maybe not great. When you take a course pass/fail, your grade will be satisfactory if you meet all the requirements and do a reasonable job, or unsatisfactory if you don't. Try not to confuse satisfactory and satisfying.
"Satisfactory" means that something is adequate, or acceptable. Whereas "satisfying" means that something meets your needs or requirements and has positive associations.
The phrase "far from satisfactory" is correct and usable in written English. You can use it to describe something that is not satisfactory or not satisfactory enough. Example: The results of the experiment were far from satisfactory.