Although the Lightning Network has the potential to help Bitcoin scale to millions of new users, the scheme powered by payment channels has become a controversial topic of conversation in the community. Some would rather see an immediate increase in the block size limit, but the developers behind Bitcoin Core seem intent on turning the Lightning Network into a reality as quickly as possible.
One area of dispute involved with the Lightning Network is whether the system would hamper or help privacy in Bitcoin. There have been many proposals for improving privacy in Bitcoin over the years, such as Zerocash and JoinMarket, but the Lightning Network opens up new issues in its system where, effectively, transactions are not immediately broadcasted on the blockchain.
http://coinjournal.net/bitcoin-developers-explain-tor-style-onion-routing/
