It's fair to say that Wonky Whistle is one of, if not the, worst received episodes of the show. I personally think there are worse ones from writers with more experience than Neil Ben had, but that's another story.
I recently made a Twitter poll as to whether fans would appreciate another episode written by him and the result was... interesting:
If Neil Ben was given another opportunity to write a Thomas episode, would you give it a fair chance?— Chris Tomson ♿️ (@ChrisTomson2013) January 29, 2016
It was actually very close, but 39% of fans polled were unsure whether they'd give it a fair chance, which is understandable. There's still a lot of animosity towards that episode and him (why against him, I don't know. You may not like his work, but don't attack him). However, it's nice that fans are willing to give him a chance.