Depends on the union. Most people forget there was a time when we worked weekends, had no benefits or retirement, and when 4 year olds could work in factories. Union were instrumental in obtaining fair and safe working compensation and conditions over the decades. Some unions, however, are corrupt, or simply bureaucratic, and take dues from their members without attempting to represent them and their interests.
You said personal views so: Unions are like fire. They can be very useful and helpful; but are subject to abuse. Laborers in the U.S. were subjected to horrendous abuse prior to the institution of labor unions. Workers had no voice or power to negotiate. Labor unions have allowed them to speak with one voice rather than as individuals.
Having said that, I am reminded of Lord Acton's comment that "power corrupts and absolute power corrupts absolutely." Labor Unions have obtained tremendous power, and at times that power has been abused. There are substantial allegations of the infiltration of organized crime into labor organizations; and at times unions have shut down factories rather than agree to wage reductions which would benefit everyone. On a personal note I remember flying into New Haven Connecticut in a private plane in the early hours of a winter morning; and couldn't leave until we received oil for the plane's engine. We asked two young men on the field if we could purchase oil. We were told yes, but we would have to wait until seven when the line crew came in. They were mechanics, and it was not in their job description to sell oil. We lost several hours of valuable time because of a union contract. So bottom line, Unions are a mixed bag; some good, some not so helpful.