I like that I can aggregate logs from multiple servers in one place. Setting up the Scalyr agent is really easy on your servers with minimal configurations. Scalyr is inexpensive compared to similar services on the market. I do like that the Scalyr team is continually striving to improve their product and have set up a few meetings with our engineers to investigate how we use Scalyr.

Ability to slice and dice data by tags in addition to robust querying language

Keyword search is easy. Viewing and resolve alerts also easy to use.