Hi, I moved from south east England to Scotland 3 years ago and it's the best decision I've ever made. Here's my take on it:
Winter is much the same. It's a bit darker in the mornings but the temps are comparable.
Don't listen to the poster who insinuated you'll never see the sun again, I regularly eat dinner outside in the evenings in summer. It gets dark at 11pm in summer and it's twilight until 3am when it gets light again. It is beautiful.
The water is better, the air feels cleaner up here. Yes it's a couple of degrees cooler, but it's rarely muggy and oppressive.
Everyone is so much friendlier. People love to chat. I've been welcomed everywhere I've gone in scotland. The culture is friendly and warm. There is community spirit even in glasgow despite it being a city.
Nhs care feels about the same where I am (rural-ish central belt). I travel 25 mins to my dentist and they always have free nhs appointments available. Prescriptions are free as well. As are nhs eye tests.
Our sunsets are breathtaking, the summers are so green and lush. The Highlands and borders are beautiful. It's less populated so everything feels more open. I can't describe to you the feeling of being able to see snowy mountains in the distance in the winter. It's amazing.
I feel at home when I hear a Scottish accent now. I love it here.
I think it depends on the kind of person you are. If you're looking for the freedom to walk wherever you want, the ability to strike up a conversation with anyone, and you are adaptable to the culture up here, go for it. I consider myself scottish now and would never go back to England!