Keto Diet... I need some personal opinions and not google’s!

So I have met many people who follow a keto diet. I work at a coffee shop and people often come in getting what are called keto drinks. (I tried them and think they were gross.)

What are some thoughts on the keto diet? Have you tried it? Did you get keto flu? Do you think certain people should not do keto? Is it really a long term lifestyle change or just a fad diet?

I know I can google about keto and I have done so but I want real opinions from people who have tried it, not news articles.

(I have some health issues that I’m not sure how they affect me on a keto diet; multi-nodular goiter, mitral valve prolapse, anemia and barely any vitamin D in my body, as well as my doctor telling me last week that I have some sort of sugar line on the back of my neck and could get diabetes, hence the research into keto! I’m also lactose intolerant and dairy seems to be in all keto recipes.)