I really do want to see nwiki make it into 2.0, although before it is released it must match or better the behaviour of the old wiki. Issues I've recently found out/been told about:
1. In nwiki editor group mode, students in different groups can see/select attachments belonging to other groups. This means that attachments are not private. Privacy of student's work is very important.
2. In HTML editor mode, the last time I checked, users could not add attachments to pages. I love the attachments interface from the nwiki editor. It would be be great to see the same interface in the HTML editor mode (and simple markup mode if not there). Either way, users must be able to attach files/images when in HTML editor mode.
Other than that, the only other issues I still have are fairly minor and relate to making interface elements clearer (e.g. the permissions system and set up options) and documentation. I did spend quite a few hours/days updating the English language docs and strings which can be found at: http://moodle.org/mod/forum/discuss.php?d=75018. These are mostly complete, any any gaps that remain relate to aspects that were still being developed or weren't clear to be.
I find the current ewiki a real pain and it is becoming embarrassing to me to keep saying to people that a new wiki is just around the corner. There are so many things in nwiki that I love and I think it is almost release ready with regards to functionality and interface. However, I appreciate that moodle.org also have code requirements that regular users don't see. I think that releasing moodle 2.0 without the nwiki (assuming above issues resolved) would be a travesty. Please vote for the new wiki.
Lets get this in head for 2.0.