We've been using Queue Fair for some time now but we have recently switched over all new clients onto this service which has helped us immensely with customer service as it was very easy to use and understand how everything would work.
Having the chat functionality also helps out when there are issues or problems during busy times etc. I wouldn't say anything negative about any aspect however I am sure other competitors are more expensive therefore if budget isn’t an issue then go ahead! If looking for cost effective software solution then definitely consider Queue Fair - they really do provide excellent customer support through live chats.