What do you get out-of-the-box in this distro?
Trick question: it doesn't come in a box. With Arch, you configure your operating system yourself. Arch Linux is simply the most vanilla you can get when it comes to Linux operating systems. Sure, a lot of people will discourage you to jump into it because of the steep learning curve, but it's absolutely worth it. It might take you an entire week to just install it, but just by getting into a tty terminal of your newly-installed system, you've already learned so much about how Linux works. But that's just the tip of the iceberg. With Arch, you're getting yourself in full control of your system, choosing all your configurations along the way and learning bits and pieces about how Linux and computers work in general.
Ultimately, the best thing about Arch is its simplicity and its philosophy. There is absolutely no bloat. All you ever start with are the essentials to make your computer beep. Just add what you need when you need it. And since you put everything together yourself, you can tailor each Arch installation specific to your needs. Need to install Arch on a 30-year-old laptop? Or perhaps you want a portable Arch installation on a 4GB thumb drive? Configure your system in the best way possible for your use-case.
Personally, I was attracted by Arch because I never really liked the window managers bundled with any OS ever. Replacing it with another leaves my system with unused packages I may never see again, and that just feels dirty to me.
The other beauty of Arch is its package repositories and the AUR. If it's on linux, you can probably bet that there is an Arch package for it. All the packages are just so diverse, and you can easily build your own PKGBUILD configurations if none exist for the program you need.
Lastly, Arch Linux is a rolling release distro. Personally, I find this as an advantage since it's much less of a hassle to upgrade especially when you can do it more often. It has been a very rare case that I break existing packages when upgrading, unlike on biannually-releasing distros like Ubuntu.
I really can't say too much bad things about Arch Linux. Since it puts you in control of everything, it is only your fault if something goes wrong with your setup. This is the way Arch Linux is designed and the way that it should be used.
The biggest issue with Arch is perhaps the AUR being unmoderated. The AUR repository may be full of wonderful packages, but without prior knowledge and careful checking of each PKGBUILD, there is no way of knowing if the package you're installing is trying to get root access and doing some funky business with your system.
1: I would highly suggest for you not to use bulky Arch derivatives like Antergos and friends. It certainly makes installation exponentially easier, but if that's what you're after then you're probably better off with another pre-packaged distro like Ubuntu.
2: If you're considering Arch for your business solutions (deployment servers, for example), Vagrant or other image management tools might help greatly.
3: A bit of a stretch, but I would suggest that instead of using AUR helpers, you build your packages yourself and create a sustainable way of upgrading AUR packages regularly. This way, you'd get less surprises down the road plus you'd have the ability to customize some builds if they don't work properly.
Currently, I use Arch as my primary and daily Unix OS for development. I have it installed on a portable hard drive, taking up half its capacity for storage and swap while the other half is being used as a regular cross-plaftorm NTFS storage partition. My Arch is configured to run as an alternate boot device on any modern computer, so I always have my OS with me even when I don't bring my laptop.
I am also considering build Arch images for lightweight and single-purpose deployment servers.