What is so special about it?
How dare you ask such a question after years of 2.1.8 and 3.2.9 we are at Kernel 4 and you dare to ask what is so special with it??!!
I tell you what is so special about it:
Linus Torvalds simply found the time right to start with a new number after some rather humoristic polls.
This are thoughts pf Linus Torvalds on the matter:
So, I made noises some time ago about how I don't want another 2.6.39 where the numbers are big enough that you can't really distinguish them. We're slowly getting up there again, with 3.20 being imminent, and I'm once more close to running out of fingers and toes.
So that is the criteria for version 4 - Linus ran out of fingers and toes
Other than that the kernel works well. With Manjaros Kernel tools it is easy to switch kernels and test them.
Have a look here
You can do it in the CLI or with a GUI.
Manjaro updates do not change the Kernel version so if you have installed Kernel 3.16 then your Kernel might be updated to 3.16.2 - never to 3.17.
This confused me a bit when I started using Manjaro but it is great for keeping your systems stable.
(My Manjaro install is rock solid and stable even if it is a rolling release distro.)
So I installed Kernel 4.0.0-1 in addition to 3.16 and 3.14 that I also have installed.