This is the "let's hang a chlorine on some sugar" sweetener right? It always struck me as implausible that it would be biologically inery.
If the structural formula looks like a pesticide it might be better to not ingest it.
When I first saw discussion of sucralose that was my response-- 'wtf, that looks like a pesticide'.
Then I found out how it was discovered: A chemist misheard 'test the compound' as 'taste the compound'. ( http://www.laleva.org/eng/2006/12/the_history_of_splenda_the... )
But the fact that it obviously looks like probably-bad-news is probably good news for its safety: It has been very widely tested, including by a lot of people who were expecting it to be poisonous. And in spite of all that testing and deployment to the public in enormous quantities, there is little to suggest that it isn't safe. If it does turn out to have negative effects, they can't be that significant or serious or we would have noticed by now.
The negative health effects of sugar are well established. To the extent that sucralose is displacing sugar it's almost certainly a net benefit.