Here is my 3-month keto experience before I got married in a nutshell:
The awesome - I lost a few pounds and toned up quite well. Had tons of energy and mental focus all the time. Salt had no effect on me, and neither did caffeine. My hair and skin became much softer due to the higher oil intake. My extreme sensitivity to loud sounds went away actually, which was an absolute blessing to me (I can now listen to music again). Cravings for anything sugar, which are already pretty low to me, disappeared. You just don't crave carbs. Overall it was amazing.
The not so awesome - The diet requires a lot of preparation. Keto flu was vicious, albeit short lived. There's also an intestinal flora change that occurs in the first few days which will make your stomach feel upset at the beginning, but it goes away. I love beer and you just can't have that while on keto. Carb based diets have significantly higher variety and availability in fiber. I really, really had to purpose eating high fiber keto-friendly foods like avocado regularly, and as much as I love avocado, it can get old. And, uhh, I'll say it again, but no beer. 🙁
I did go back to my lean meat, fruit, and vegetable heavy diet, but I consider the experience to be really cool. It's a very, very effective diet that works, and it limits your ability to eat fast food and other junk. It creates an extremely stable blood sugar environment for your body, and it will work wonders for various different health conditions that affect the brain and pancreas.