I think the lens can be decent, but also think it can be a bigger crapshoot with quality and matching the lens to the camera. For me I went with the Canon just because the odds were more in my favor of not having to think about the lens, whether it had more CA, was slightly off, or had build issues.
Now when it comes to a lower price point, then I start looking more seriously at them.
For me, I am just hoping that they improve their quality a little bit and offer stronger competition. Always nice to have this to not only drive the market for improvement, but to keep prices from being inflated... For the record, I have been an AMD guy over Intel for close to a decade... More performance, cheaper price.