I spent 18 days in Indonesia and as much as I liked it, I'm also happy to be in Bali's airport and on my way out to Singapore.
Traveling Indonesia is really a great experience and I am happy to have witnessed this culture and could only advise you to visit the country as well, but...
It is a very hard country to travel in. Well, this goes for if you travel on a budget and you most likely do. If you're happy to pay the asked price for everything you'll have an amazing time. You won't be getting your value for money though.
But for people on a budget, you must go to Indonesia with a bucket of patience and a bucket of dignity, and get ready to dump them out.
This goes particularly for Java island and it's said to be even worse on Sumatra. Bali was a bit easier to get around but my patience was still put to test daily.
The problem is you're taken for a waking wallet stacked with bills when in reality the people they get to see in the average restaurants, hotels, stores and beaches are the poor ones, and they just don't get that.
In negotiation there is something called anchoring. Anchoring is the fact of announcing a price first for it to be the starting point of the negotiation. People only pay the value they consider a particular item or service is worth.
In Indonesia, they anchor prices ridiculously high, making negotiations really though. My best advice is to take a few days to be able to estimate values yourself, your value. Then when you want something, whether it's a bottle opener or a coconut, beat them to it by just walking up to a shop with your estimated value in cash in your hand and say: "I'll give you xxxxx IDR for this." If they say no just walk away. If the sales person announces a higher price wave the bill(s) your willing to trade and say "This is all I got." If you're not aiming ridiculously low they'll accept it or say no only to catch up with you, sometimes grabbing you by your arm, and say "Okay okay."
On a regular basis I got prices divided by 5, going from 250k to 50k IDR for a fake Hurley T-shirt for instance.
The bucket of dignity is for the way you'll be treated and spoken to. Once you've paid you're like cattle and will be yelled at: "Go here" "Go there" "You stay" "Get off"
More than once, particularly during my booked package trip from Yogyakarta to Denpasar, I was spoken to and treated as if I was shit. This is not an exaggeration. Many people to whom I spoke to felt the same, including the ones who were on the tour with me, and some, in extreme cases, couldn't wait to "get out of here." The worst is that you can do nothing about it. It felt like swallowing a bitter mouthful.
Overall, I don't understand the hype around Bali in particular and wonder how it reached its status of a great vacation destination. Marketing perhaps. It doesn't deserve half of it and people are starting to be aware of this, as tourism is plummeting in Indonesia.
The beaches are of a grayish unfriendly color and are mostly hostile with rocky/sharp dead coral bottoms or big waves such as in Kuta. There are plastic wastes in the water and scattered on the sand everywhere I went. The white sand paradise beaches must not be the reason you're going to Indonesia or you'll be disappointed.
That being said, I went for understanding the culture, the people, having an experience in a different country, and I am still disappointed. I had a great stay thanks to my friends and myself, not the locals who highly contributed to the downfalls of these last 18 days.
If it was to repeat I'd return, but only because I've been to 62 countries and wish to see them all. If it was my once a year vacation trip I wouldn't go through the frustration of traveling Indonesia, ever.