Ben Sigelman, one of the founders, is a former Googler who's got tons of domain knowledge about profiling distributed systems of services and about how to structure calls and dependencies within those systems. He gave a fun talk at the SF Golang meetup in 2014. I, personally, am very excited to see what he's up to and will be keeping an eye out for more Lightstep stuff - I guess it's his newest thing.
(if you're reading this, hi Ben! Sorry we never got together last year)
... follow up, what's everyones opinion on this?