I like the original massing better as well, though it is common for this piece to evolve based on the needs of the end user and as programming requirements are confirmed. It's less architecture and more a result of the functional space.
Overall though, I am very pleased with the design and the fact that the Art Gallery is moving along after over a decade in limbo. I like the metal screen approach they've chosen to go with from a durability perspective, providing a sense of permanence, and for easier maintenance. I can imagine the materials' lustre in different lighting conditions. The warm colour palette is also a nice change and should be a standout from our cool tones.
I find contemporary design often overwrought but i think the attention to detail here (materials, weave patttern) will make or break the end product. I have some faith that it's Herzog.
The process describing how the design was arrived at and the options considered is described in detail here:
https://www.herzogdemeuron.com/projects/438-vancouver-art-gallery/#process