My experience with E-Prime began with a challenge predicated on the idea that the copula stands in for far too many verbs, and that by limiting the use of one verb, the heterogeneity of the remainder increases. Viewed in that context, I think E-Prime provides some benefit.
It does sometimes lead to belabored wording, and demands more careful consideration during composition. However, when regarded as a tool for encourage more thoughtful word choice, and in contrast to the explicitly stated goals of "Newspeak", the use of E-Prime increases the 'area of choice' and broadens the spectrum of vocabulary used in practice, if not in theory.
It does sometimes lead to belabored wording, and demands more careful consideration during composition. However, when regarded as a tool for encourage more thoughtful word choice, and in contrast to the explicitly stated goals of "Newspeak", the use of E-Prime increases the 'area of choice' and broadens the spectrum of vocabulary used in practice, if not in theory.