Gradle is the best general purpose build system I've seen, a bit of initial overhead but as soon as you need something more than basics you're very glad it's done the way it is. Not without flaws but better than other "API" build systems I've used (WAF, CMake)
What Gradle advocates present on their sessions about leaving a running daemon, configuring the JVM memory, changing the way the build is done and so on....
I like Gradle too, although I very much recommend having a look at QBS (Qt Build Suite, although unlike Qmake it's not really bound to Qt and can be used for general build scripting). I've used it about a year ago and was really amazed to see what was probably the first sane build tool I've used for years. Of course Gradle is rooted in (yet not limited to) the JVM ecosystem and QBS started as a C++ build tool, so they are not really equivalent, but comparing the ease of use, predictability and the overall impression, QBS beats Gradle by a full grade in my opinion.
You do know Gradle uses Groovy as the syntax for its build files, right? The people behind Groovy had a problem a year ago where they were retrenched from their jobs working on Groovy, and haven't found any businesses since then who'll pay them to continue improving Groovy. Gradle doesn't mention Groovy much on its gradle.org website, perhaps out of embarrassment.
