To be honest with you (and I assume if you ask for feedback, then you want honest feedback), it does not look very professional or appealing. You could get someone on fiverr (https://www.fiverr.com/s2/4598cf9d0b) to create a good one for 5$ or if you want to make it yourself, look at the top books in your category on amazon and look how they designed their cover.

Things that could make this cover look better: Do not use two different blue colors which really can't exist next to each other for fonts. Put the sub-title somewhere else, and / or remove that greyish-blue background at the top. Refer to the golden ratio design rule to place elements (more on that here: http://www.creativebloq.com/design/designers-guide-golden-ratio-12121546) I hope this helped!