Other tools, fogbugz, trello, etc are very good at what they do.
Invariably though when you get enough projects that are complex enough (not always big), JIRA has been the only thing that could take a bite out of managing the details like few others.
JIRA also can be greatly simplified to use but most users don't do this. The JIRA core offering is what I recommend to folks. JIRA is heavier for dealing with heavier projects.
On the flip side. Having a search engine of every issue and decision, be it design, system, implementation, roll out ticket for every project in a company is second to none.
I recently assisted a client in their systems design and growth from from 0 to 50m revenue in 4 years. It feels strange and wondeful to have every decision made in one searchable place, on one time line for every major piece of software or system implemented for them.