Monitor processor, memory, disk, bandwidth etc along with standard checks such as HTTP, Ping and FTP
Create alert groups and receive notifications when unusually high load or bottlenecks occur.
Keep track of website response times and automatically link performance graphs to incidents.
Seemless CloudWatch integration and simple monitoring client download for all other providers.
Long term reference:
We keep your data for years, you don't need to manage storage and you get to dig into historical data any time you like.