Gold's value starts with the fact that its supply is steady and by nature it's durable. In other words, the amount of gold traded each year (The Supply and Demand) is small relative to the existing total stock. This acting as a bit of a throttle on its value, as does the high cost of mining. Mines will have yields that control whether it's profitable to run them. A mine may have a $600/oz production cost, in which case it's clear they should run full speed now with gold at $1200, but if it were below $650 or so, it may not be worth it. It also has a history that goes back millennia, it's valued because it always was.... John Maynard Keynes referred to gold as an archaic relic and I tend to agree. You are right, the topic is controversial.
For short periods, gold will provide a decent hedge, but no better than other financial instruments. We are now in an odd time, where the stock market is generally flat to where it was 10 years ago, and both cash or most commodities were a better choice. Look at sufficiently long periods of time, and gold fails. In my history, I graduated college in 1984, and in the summer of 82 played in the commodities market. Gold peaked at $850 or so. Now it's $1200. 50% over 30 years is hardly a storehouse of value now, is it? Yet, I recall Aug 25, 1987 when the Dow peaked at 2750. No, I didn't call the top. But I did talk to a friend advising that I ignore the short term, at 25 with little invested, I only concerned myself with long term plans. The Dow crashed from there, but even today just over 18,000 the return has averaged 7.07% plus dividends. A lengthy tangent, but important to understand.
A gold fan will be able to produce his own observation, citing that some percent of one's holding in gold, adjusted to maintain a balanced allocation would create more positive returns than I claim. For a large enough portfolio that's otherwise well diversified, this may be true, just not something I choose to invest in. Last - if you wish to buy gold, avoid the hard metal. GLD trades as 1/10 oz of gold and has a tiny commission as it trades like a stock. The buy/sell on a 1oz gold piece will cost you 4-6%. That's no way to invest.
