Pro Shell commands inside Grunt
There is a Grunt plugin called grunt-exec which allows developers to execute shell commands inside their Grunt files. This is extremely easy if a developer is developing only in Node and constantly getting out of Node environment to run something like a git command can become frustrating.
Pro Grunt v1.0 alpha uses Orchestrator for maximum concurrency
Grunt version 1 alpha, aka grunt-next, the upcoming next major release of Grunt, uses Orchestrator to sequence and execute tasks and dependencies with maximum concurrency, potentially bringing it up to speed with Gulp in term of performance.
Con Large bloated configuration files
To configure Grunt, developers need to basically write large files and configure JSON objects. While it's very powerful, the sheer complexity of it's configuration file may be a large obstacle for newcomers and developers that have not used any automation tools before. This may push them to search for simpler alternatives.