Regardless of anyone's views on trans issues, I think it sets a dangerous precedent that Westminster can overrule the devolved governments.
It's not a precedent it was built into the act that created the devolved governments. Some things are devolved and some not.
I think it's unfortunate that it has arrived with this bill, and it will be interesting to see how it affects people's attitudes to Scottish Independence. There will be those who don't care what the bill is about but "how dare England try to block our laws" about this, and others who are concerned about the content of the bill who may be either "how dare they" or "thank goodness"
The fact that we are 4 countries under the banner of one nation isn't even unique. The US and Germany are two examples of federated states where the states have certain devolved powers, but not over every aspect of life. And they are definitely not allowed to enact laws that encroach on the powers of the national government. I haven't really paid that much attention to the bill in Scotland, i do know that for various reasons it is heavily contested in some quarters and highly desired in others. Not necessarily because they are trans/anti-trans (or pro-/anti-woman - depending on your view) but because it is a test of how far the Scottish government can and will go to preserve/extend its autonomy.
From a Scottish citizen's pov, of course, the more autonomy their government has the better (if they support Independence) and the less their government has the better (if they don't). From the UK government pov? it's a hot mess giving some citizens different laws than others. How do we handle having a GRC issued in Scotland when we're in England or Wales? What if someone from England moves to Scotland, 3 months later gets a GRC and subsequently (as planned by them) moves back to England?
Marriages in one state are generally, but not always (as we have seen with same-sex marriage). Marriage is, like a GRC, in essence, a government licence to confirm an action an individual has taken. So how does it work in countries where a GRC isn't recognised at all? or has very different criteria? (i have no idea but could imagine that some states might say you only get a GRC post all surgery, for example, and I'd think that may be a problem for some)