Speed reading is a useful technique for quickly absorbing the information within a book or article by essentially skimming through the page.
It shouldn't be seen as a better way to read but rather as a tool which can be useful in certain situations. Personally, I find speed reading only applicable to non-fiction books with low-density of ideas and information.
While reading information dense books it is very difficult to read fast. In fact it can be useful to read small sections at a time and then spend time thinking about the ideas and information. There's simply too much to take in and internalize to skim through the book fast.
However, while reading books with low-information density the main points and ideas are spread out thinly over large sections and chapters. This not only makes it possible to read quickly, but also makes it possible to think and reflect while you're reading. I have found that once I eliminate the "reading voice" inside my head, I can have my own stream of thoughts on top of those which I am taking in from the book. This turns the act of reading a book from simply absorbing ideas and information into a sort of discussion between my own thoughts and those of the book. The book becomes a sort of path or guide for my thoughts, like a guided meditation on a topic!
Quiet Your Inner Voice
When reading, most of us have an inner voice which "speaks" each word in our mind as we read. This can be useful for remembering and internalizing information but also limits the speed at which one can read. Thus by quieting this inner voice, it can be possible to read much faster than before.
One method for quieting your inner reading voice is to read in images. Instead of looking at a word and hearing it in your mind, try practicing looking at words and seeing them in your mind. If you read "cow" try imagining a cow in your mind without voicing the word itself.
Moving your finger along the page as you read can be incredibly useful for reading faster and helps to quiet your inner reading voice. Try to keep your finger moving along the page faster than your thoughts can "speak" the words.
Once you get the hang of moving your finger horizontally along the page, the next step is to track your finger vertically along the page. Keep your finger at the margin and move it down slowly while you keep your eyes at the same level at the center of the page. Try to absorb the ideas from each line or paragraph while keeping your eye focused on the center of the page. If necessary, adjust how far away the book is from your eyes so that you can comfortably absorb line by line rather than word by word.
This vertical finger tracking is the technique which I use most when speed reading. Some "speed reading experts" boast being able to read an entire page in one glance but this seems a bit far-fetched and definitely not necessary. With the vertical finger tracking technique I can comfortably read each page in about 7 to 15 seconds each and get through 100 to 150 pages an hour with some pauses to follow stray lines of thought.
Find Key Paragraphs
Another technique that I have heard mentioned is to find the key paragraphs and read them slowly. This could be the introduction and conclusion of each chapter for example. Then either skimming the rest of the book (or just the sections you're interested in) or skipping it entirely. I have not used this technique myself so I cannot speak to its effectiveness.
If you are ultra-savante, simply take pictures of each page in your mind and revisit the information whenever you want. It is said that Nikola Tesla could recall and recite passages from any book he had read by simply conjuring up the image of the page in his mind and reading from it.