Just dropping a quick review of my initial impression.

What it does:
- Monitors your website's uptime AND response time
- Tells you which plugins are causing PHP errors
- Basic security/health checklist
- Emails you notifications

Pros:
- Clean interface
- Web portal for checking all websites
- Generate client reports
- 1-min ping intervals
- 16 regions to choose from for performance/ping testing
- Identify plugins causing PHP errors

Cons
- None

Overall, this is a solid plugin you should get. The PHP Error feature is the most unique. WP Umbrella makes it so much easier to check this than Query Monitor or your server logs.