1. Auto-align MUST be improved, align_image_stack (part of Hugin) gives MUCH better results!
2. De-ghosting, please! (branches swaying in breeze produce terrible artifacts!)
3. Batch processing
4. Better interpolation, to prevent jaggies (look the pictures below).
This is how it looks in Essential HDR 1.0:

And this is how it looks in Bibble Lite:
