PPM is a big category
SMOSLT does not attempt to compete with other PPM software. There is plenty to compete with. Use what works best for you.
SMOSLT can be compared with other PPM tools
SMOSLT’s place in the mix is to be fast and relevant to both developers and project managers.
SMOSLT is intended to be ridiculously flexible and adaptable. No good software can do that. That’s why SMOSLT is, happily, such crappy software.
A fantastic list of other PPM tools is compiled here