Below are the Pros and Cons of Appium:
Pros:
For programmer irrespective of the platform, he is automating ( Android or iOS) all the complexities will remain under single Appium server
It opens the door to cross-platform mobile testing which means the same test would work on multiple platforms
Appium does not require extra components in your App to make it automation friendly
It can automate Hybrid, Web and Native mobile applications
Cons:
Running scripts on multiple iOS simulators at the same time is possible with Appium
It uses UIAutomator for Android Automation which supports only Android SDK platform, API 16 or higher and to support the older API's they have used another open source library called Selendroid