Is there any good API for accepting and sending Ethereum like blocktrail for bitcoin ? Why is working with Ethereum so complicated?
Ethereum works differently so there is less need for APIs for accepting and sending Ethereum. Working with Ethereum is not complicated, it just requires different approach than other cryptocurrencies. You need to throw away some false assumptions and relearn different concepts.
There is less need for server-side payment processing, because smart contracts and Solidity events can be used as a signal of completed user completed operations, like payments. Listening to the events can be done over JSON-RPC.