I have a mixed feeling about BTRFS. On one hand, its beautiful features means that it is very appealing to enterprise users, which are going to use them to their full extent. On the other hand, the typical enterprise usage scenario include a lot of rewrite-heavy applications, as virtual machines and database systems. When coupled with standard mechanical disks, BTRFS is going to disappoint in these roles.
You can say that consumer application are generally much less rewrite-bound that enterprise one, and you are right. However, do the standard home user really need BTRFS exceptional features? I think no.
So, you end with a enterprise-targeted filesystem that fails in the typical enterprise workloads. Ouch!
Don't let me wrong: BTRFS is a wonderful filesystem, and just to get a CoW filesystem working reasonably well on mechanical drives is a tremendously hard effort. The simple fact that BTRFS is useful in many situation is a testament to the very good programming work behind the scene.
However, it seems that BTRFS really need an SSD to show its full potential. With extremely low access time and no fragmentation problems, SSD are the perfect platform to use BTRFS to its full extent without performance drop.
Imagine a Linux-KVM server with loads of SSD space and BTRFS managing all them. Mmm... fantastic vision. However, mechanical HD are going to remain the primary storage tech for many coming years. If BTRFS don't improve its performance with mechanical driver, it will be quite difficult to adopt it as the default, generic filesystem of choice.
Have a nice day!