Recs.
Updated
SpecsUpdate
Pros
Pro Focuses on code instead of configuration
This depends on your style, but gulp is closer to the code, the actual execution isn't hidden by multiple layers and it's much easier to customize the build system without writing bloated modules. This also brings rather small configuration files.
Pro It is possible to use projects that use streams without plugins
Since Gulp just uses streams at its core, you don't actually need a plugin wrapper to use a project that uses streams. If you use this approach, the you don't even have to worry about plugin maintenance at all, and get the bleeding edge updates as soon as they come out even if the plugin hasn't been updated. It also means if a project happens to not have a plugin, you don't need to write a new one, you can just use it as is.
Pro Streaming build system makes it easier to apply code transformations
In gulp, it's easy to pipe multiple steps together which you commonly need with build systems. For example, you may need to compile the javascript source files, then package them together, and then minify it. The streaming system makes this much easier.
Additionally, it improves performance since all operations are done in memory (compared to I/O operations) and avoids the need of unnecessarily compiling files (compared to Grunt that has to compile all files even if just one has changed).
Pro Minimizes disk operations for improved performance
Because Gulp is built using streams, it can store intermediate transformations in memory and defer writing to disk until the very end. This improves performance by not requiring expensive blocking disk operations for task dependencies.
Pro The configuration file is easily readable
Gulp's configuration file is actually very readable because it's actual JavaScript instead of a large file of JSON objects. The entry barrier is very low for developers who have never used a task runner before and it's API is very simple, with only 4 methods.
Cons
Con Rapidly changing API
While it's good that the gulp maintainers want the api to be as good as possible, it comes at the expense of stability. The upcoming gulp 4.0 release has another update to the way dependency management works which will require everyone to update their build scripts.
It also makes it hard to look up information on best practices as the best practices keep changing, making a lot of the blog posts and questions about gulp out of date.
Con You need to know some limitations that are not very intuitive
There are some features in Gulp which may not be very intuitive, or that otherwise should have been the default features instead of having to implement them through arguments. For example, to keep the correct folder structure when you are copying a file, you have to add {base: "lib/"}
as an argument.
Recommendations
Comments
Flagged Pros + Cons
Con Still young
While it has gathered a large following and it has a decent number of plugins. Gulp is still relatively young.
This means that Gulp may not be ready yet for large production sites because it is still missing some plugins which are available for other tools of it's kind.