Erik,
I doubt if any of us here on the forum has any meaningful data to support or refute a statement that "most of us agree" that Numbers 3 is a "disaster" or "backwards." Different people use an application in different ways, and I would guess recently there a lot of new people trying it out now because it is now free.
The new Numbers is a *huge* improvement for businesses that want to do data entry on mobile and have it sync back to the Mac or that want some degree of on-line collaboration. The old Numbers was unfortunately crippled in those key areas of productivity enhancement.
The new Numbers is not as good as the old Numbers for people whose spreadsheet use is geared toward traditional printing of highly formatted documents, or who have become heavily attached to some of the niche features in the old version (though there are many workarounds).
The fact that the new Numbers does not implement splitting of cells is arguably a good thing. That encourages good spreadsheet design. Splitting and merging cells spells trouble. There are always ways to achieve the same effect in other ways.
SG