Image quality

How does Darktable compare in image quality to Lightroom? Lightroom has a well-tweaked RAW converter, per-camera/lens adjustments and lossless internal processing path, but it suffers from limitations that seem to be deliberately intended to avoid cannibalising Photoshop sales (only round brushes, limited adjustments available via brush, only basic curve-editing, etc.)

I'd love a more flexible, geekier Lightroom-like application, but not at the expense of image quality...