L2TP stands for Layer 2 Tunnel Protocol, which, by itself does not provide any privacy or encryption to traffic passing through it.
Due to that fact, it is usually implemented together with IPSec suite of protocols to encrypt data before transmission, providing users with privacy and security. All modern VPN compatible devices and operating systems have L2TP/IPsec built in.
The setup is as quick and easy as PPTP, but there can be problems, as the protocol makes use of UDP port 500 which is easy to block by NAT firewalls.
Find out more about L2TP on Wikipedia