Most often I seem to get into this chain reaction: happiness is getting low and I start to lose people (or not getting enough of them) which leads to everything failing OR to increase happiness enough I need to use quite a lot of resources to cover the building costs. I tend to start running out of food at some point. Often it takes most time to get enough fertile soil for farms, depending on the map of course.
However, it's also possible that I haven't learned the right balance yet...
To my opinion, the costs of buildings is a lot more balanced now than in the previous version.
PS: I've been only playing on "normal" mode.
I analysed my difficulties more and noticed that the negative happiness spiral is always the following:
1) Happiness is going doing.
2) Raising happiness would require buildings which need a high number of people (parks and restaurants).
3) Because of the happiness level, I can't get enough people to join my colony to raise the happiness.
4) Happiness keeps going down which is the end OR I ran out of food because farms also require people.
Improvement suggestion: Adding a building option to improve happiness which doesn't require people at all.