What separates the modern movements is not whether halakha is valuable but whether it obligates.
Orthodoxy holds it binding in full and divinely grounded. Conservative Judaism holds it binding and revisable, and its Committee on Jewish Law and Standards has issued rulings permitting driving to synagogue on the Sabbath where distance would otherwise prevent attendance, ordaining women from 1985, and admitting openly gay candidates to ordination from 2006. Notably it sometimes issues more than one valid ruling on a question, which is itself a statement about how the system works. Reform treats ethical law as binding and ritual observance as a matter of informed choice.
The practical consequences are severe where personal status is concerned. Conversion, divorce and descent are governed by halakha, and Orthodox authorities do not accept non-Orthodox conversions or divorces, so a person may be considered Jewish by one movement and not another, with real effects on marriage and, in Israel, on law. Reform's recognition of patrilineal descent in 1983 sharpened this considerably, since the rabbinic rule reckons Jewish status through the mother.
Two comparisons illuminate what kind of thing halakha is. Islamic sharia is the closest analogue in any tradition: a comprehensive law derived from scripture and prophetic practice through jurisprudence, covering worship, diet, family and commerce, with schools of interpretation and no single authority in the Sunni case, and the parallel extends to the historical fact of Jewish and Muslim jurists working in the same intellectual world. Christianity, by contrast, decided very early, in the dispute recorded in Acts and in Paul's letters, that gentile believers were not bound by the Mosaic law, and Christian tradition therefore developed canon law as church regulation rather than as revealed legislation binding the whole of life.