Ill answer the question as best I can and answer all your questions individually.
How much have you made from all this?
Overall I have made around 150euro. That is split 50%/50% between adsense and amazon.
This may not sound like much but my earnings have increased dramatically each month. The idea is that one day after a lot of writing Ill be earning a steady monthly income. However, I never expect it to be my only form of income.
Is it really worth it?
If your speaking in purely monetary terms its definitely not.If you think if it as a place to learn as well as earn a little then it is worth it.
I try to think of it as place to learn about SEO,web design, adsense and improving my writing skills. I also have other websites away from hubpages that I earn a little from. I am also planning on studying a masters in ebusiness, this website a good training ground for bigger things.
I hope that explains it. Nearly everybody has a different reason for being here. Some are here purely for the money, some just want their work read others are using it as a way to get people to visit their site and buy a product. Im here to learn and earn at the same time.