Steer clear.
Horrible. My first booster had issues with his client, the second one promised I'd be placed in gold, and the third one made me wait ages and lost me 2 placement games in a row. They all claimed to be high diamond/master/challenger players but they played like silver. On top of all this their 'guaranteed winrate' of 70% was NOT met by them, as I recieved 6 wins, and 3 losses, which is infact a 66.6% winrate, I know it's not much lower but when they boast an 86% overall winrate and are confident enough to *guarantee* 70%, I expect them to stick to their word. I was placed in Silver 1, so the second booster's promise never came to fruition. At the end of all this I contacted support for compensation for them breaking their guarantee, and their booster breaking their promise to me. I was told that there was 'nothing they could do' and that 'the service was delivered'. I will not be paying these people money ever again and I suggest you look elsewhere.