The result is surprising (and maybe not :)). If you use the "native" formats (e.g. ODF, .key/.page) everything works fine. Obviously things get more interesting, if you want to use these tools to read and write MS-Office files (.ppt/.doc/.xls) or even MS-Office 2007 files (.pptx, etc.).
In this case it is my experience that you (still) have to limit yourself to a (non-obvious) subset of the functionality to make sure you can import/export your files to/from MS-Office. Especially for Powerpoint 2007 files I currently have to use all three tools and see, which tool will give me the best result, when I import .pptx files. In some cases entire slides show up blank. In other cases they are "reformated" in a way that makes them unreadable.
Buttom line: It seems that for the time being, neither OpenOffice nor NeoOffice is a solution on its own, when it comes to importing/exporting to/from MS-Office. But that may change in the future.