Fischer’s A Grammar of Classical Arabic is a reference work which may, in some respects, be considered a modernised Wright’s Grammar.
Fischer uses modern grammatical terminology, and the examples he uses are also more “practical” or day-to-day, as opposed to the emphasis in Wright’s Grammar on examples from literary works and from the Qur`ān.
However, the examples are fewer, and, perhaps due to Fischer’s attempt to make them relevant, often do not illustrate the grammatical point being made as well as Wright.
Unlike in Wright’s Arabic Grammar, Fischer has not included a section on Prosody.
Overall, this certainly is a useful book to have, but one can’t help feeling that Wright’s Grammar, for all its archaisms, is a better book.