I used to be IBEW (no longer an electrician). Unions have some good and some bad, but at the end of the day, I'd go back union if I were going to re-enter the career.
Non-union experience: Worked at some decent shops, but worked at some really bad ones as well.
Worst stories: Being on a crew with roofers that were brought in to perform handyman electrical work on a new hospital construction. I also worked with a guy that had had his eye and half his face destroyed on the job be an industrial fan, and was forced to keep working with his puss-dripping eye for months while they sorted out the insurance... no standards, cutting corner, no concern for the worker or the workmanship.
Union experience: Most shops I worked for were very reasonable and really took care of the workers. High standards, great benefits, great pay... Big jobs though can be full of politics and ethically questionable things.
Worst story: large plant job, attracting every traveling alcoholic and shady individual with a union card. Job was overflowing with politics and lazy, unreasonable babies...
Bad and good for both, but I'd go back union in a heartbeat if it was a long term move.