I've a complicated history here. As a Brit growing up in the 1970s when the unions made life miserable with power cuts and high inflation because of their demands, I was not a fan. Yet by 2000 I was a union representative following my public sector employer's attempt to enforce massive pay cuts on some staff as a result of a 'job evaluation' exercise. I joined at that point. A few years later the existing rep moved to a new job outside the IT section and I got the gig.
On a good day unions can ensure the better operation of the firm. They enable concerns to be transmitted upwards and challenges raised. Unfortunately too often they get too powerful, start to throw their weight around, and do things that are destructive of the firm in the long term. I had opportunities to be obstructive for the sake of it - but resisted. But I did challenge crass behaviour to good effect at times.
The IT industry didn't need unions because the demand for our skills meant that we could easily move on. Now it's getting tougher and firms will be tempted to bully staff because they don't have an easy alternative: 'Unpaid overtime, unpaid on call time, etc. etc. So - given the option - join. Use the power wisely.
I'm retired now - and very grateful I'm not facing this crisis. Best of luck!