Have you taken any? If so, what were the results and how much did you pay for them?
MK-677 costs about 30 dollars for a month supply at maximum dose and equals two months supply for more a health and healing dose. It can give the equivalent of 2 IU's or even more of HGH in tablet form and also increases IGF more at higher doses, without injections and need of insulin (except ideally a supplement to reduce sugar levels such as Alpha Lipoic Acid).
Ideally it should be started at lowest dose first and cycled, though taken at almost one year non-stop there were no negative side-effect except some water retention but when coming off those muscle gains are kept.
For instance, usually when travelling, 5 kg's of weight is lost due to hardly training and walking a lot and not following ideal diet. But it's possible for the weight to stay the same without added fat even after a month travelling.
Recovery from gym is much quicker, sleep is deep and wake up re-freshened, skin looks better, energy is higher. Appetite increases though but this subsides as does the worst of the water retention, but with a dose of 5 mg there is hardly any and at 10 mg it is slight. 20 - 25 mg would be a bodybuilding dose to really build more muscle.
One of the main advantages would be healing from injuries, really helps with tendon and joint issues. Also, lower-effort training with lower weight, possibly even gives same results when training heavier natural, so especially when injured or recovering, can still look decent.
I would not go on non-stop though, always good to give the body a long break after a cycle.