I agree that Grunt syntax is not fantastic. It has improved since 0.4 but the reality is that the average "long" Grunt build has a whole ton of customization thrown into the mix that is simply not possible with newer tools such as Gulp or Fez.
Additionally I really don't think that the comparisons are fair. Yes, it's nice to declare a fileset and define transformations on it, rather than defining transformations and declaring which files you want to use with each one. But I could easily show you an easy-to-read Grunt configuration that is just as simple as the ones you see in Fez or Gulp marketing.
I applaud what these tools are attempting to do, but we need to keep the comparisons fair.
The advantage of Grunt is that it has a huge ecosystem. But Gulp has many of Grunt's heavy-hitters building plug-ins for it. So you can look at Gulp as front-end-build-tools v3.0 (Addy & Paul Irish were pushing Ant before Grunt).
This is the first I've heard of Gulp though. Looks promising.