I think, SBT is better than Maven. It allows interactive development.
SBT is not adequately documented, relies too much on symbol-heavy syntax, and allows arbitrary code in build definitions.
And there is an oft-documented overuse of custom operators among Scala programmers, however I don't have sufficient expertise to gauge the resulting problems in practice.
I did; in fairness I don't think I've ever seen one in a maven pom.xml