We are using Wheelock's in my Latin classes at a local community college. We did chapters 1 through 20 in the first semester, and are trying to finish the book in the second semester.
Having learned previous languages in the past (both formally in school and autodidactically), I think Wheelock's has many problems. I believe, though, that many of those problems stem from the idea that, "Latin is to translate Cicero into English; it is not something to use". I vehemently disagree with this idea. A language exists to be used for communication. Sure, Cicero communicates with us across millennia with his written words, but that can't be all. Languages must be spoken. For this reason, I bought "Familia Romana" and listen to things like Nuntii Latini and the Latinum podcast. I do know some Latin speakers, and occasionally try what I know on them; their gentle corrections are a great help. Latin must be used, not just translated.
Also, Wheelock's seems to have skewed priorities with regards to grammar, in my personal opinion; its organization and order could be much improved, I believe. Many in my class are lost or behind; I'm only doing well because I have previous applicable experience and study Latin on my own for my personal enjoyment.
Based on what I know about language pedagogy, Latin, and Wheelock's, were I teaching a class, I would probably not use this textbook.