Hmmm, there are three reasons I don't like
Ernestine. I don't like the name
Ernest, it along with
Nestor has the word 'nest' in it, which reminds me of straw and bird mites.
Secondly it seems unfortunate that
Ernest is being teamed with the suffix -tine, a suffix I don't like the sound of. The only remotely fine tine suffix would probably be
Augustine. (the suffix -tina is a whole different story)
Thirdly is the sound of it all together is very awkward and uncomfortable to my ears.
Now, having said that, because
Ernestine is an old fashioned name, it has a reasonably wholesome feel to it. Therefore, I wouldn't be dismayed to see it on a baby today. It would probably still think it sounds horrible, but be refreshed to see an old fashioned, unpopular name on someone. You know?