Vendors of software are quick to provide you with references, but those may be hand-picked accounts that are highly unlikely to say anything other than compliments.
Far better to scout around and find users of the software that the vendor did not provide as references. Question the vendor’s reference accounts about other licensees and then talk to the others. Experienced consultants can also provide names, as might the vendor’s website.
Once you find another client of the vendor, ask the person who uses the software the most you’re probing questions. High ranking lawyers have views, but from the operational side of things, the person in charge is the best source of information. Above all, ask them what they do not like about the software and what they like about it. Ask them about the support the vendor provides. The insights of actual users are by far the most valuable information you can collect before you make a selection.