It's been a while since I used it, but one thing that might help would be to look at the interface the for Alarms in Android. It looks pretty similar, but it's a little bit different, and I think a little bit easier to use.
Moonshot: Let users snap a picture and use OCR to suggest times that user can then edit.
Another idea to make it a bit easier for businesses with odd hours: A option for a wizard.
Something like:
1. Click here to start Wizard
2. Monday: Select open time (or say not opened)
3. Monday: Select closed time
4. Monday: Option to add another time block
5. Tuesday: Option to copy and modify times from Monday
6. Repeat
7. Option to copy time from Monday/Tuesday
8. Repeat, etc
I'm not sure how exactly this would play out, and it would only be good in the more complex cases but I personally think it would be easier.
But it seems to me case where data to enter is simply complex and I see no obvious way to make it easier.
What worse, typically multiple days have the same opening hours, so interface is optimized to make this kind of input easier (ability to select multiple days at once)
(I am one of contributors to that software)