The biggest thing I'd like to see is enabling in-page (control/command-f) search. In my quick scan through the page it looks like it doesn't do that… is that right? Are there plans to add invisible text to the DOM that control-f can find?
One problem with that is that it processes images lazily. It continually extrapolates cursor moments ~1 second into the future and processes those relevant parts of relevant images. But it should be possible that after an image is processed (or even eagerly by looking up previously recognized regions from the cached OCR server), the page could be made Ctrl+F-able.