Ketogenic diet is like anadrol - it can be a winner, but there are also some considerable downsides to it.
Personally, I have followed it twice, and both times I have had contradictive impressions. On one hand, I did have a lot of energy, had an easier time waking up in the morning, and never really had any feeling of being hungry. Lost weight as well.
However, it is extremely hard to avoid carbs in such a strict way, and it is even harder to do so for a long time. Also, there is the problem of the smell. Once your liver starts to produce ketones, your smell and sweat get a specific and well noticeable smell, which is not good. You get used to it rather fast, and don't notice it, but others do notice it.
For me, carb cycling is a better approach - it is easier to carry out, and it is very effective. Besides, with carb cycling you are not excluding anything completely.