For losing fat, fast, it's hard to beat, partly because most high carb foods: pizza, ice cream, fries etc. are also high fat. So, eliminating all these foods will result in a dramatic calorie reduction.
That said, Ketosis is a starvation response. The body doesn't want to be in it. That's why you get "kicked out" so easily. I've found I sleep poorly on very low carbs. Others have experienced this, as well. It's attributed to increased cortisol production.
From an athletic performance standpoint, high intensity training will suffer. The studies cited about low carb performance have the participants training at 60% VO2 max.The low carbs gurus like Volek and Phinney talk a good game, but all the elite runners and cyclists eat high carbs.
Bottom line: Great for quick fat loss. Unsustainable and undesirable, for most, long term.