There are two things holding me back from using tikiwiki at the moment - firstly,
1) i think phpnuke etc have the best article style (click on icon, just have topics, also can list by category) which has been suggested above, and
2) being able to discuss the post in a forum (similar to the wikis) so that comments go there and
3) having a 'newswire' - similar to Dada software that indymedias use - where anyone can post an article, but it won't go to the front page - but to a newswire and all posts to front page are features.
I am not a programmer, and therefore can't do these changes myself. I am currently waiting to transfer all my phpnuke sites across (i have about 5 that i run for others) and I have to say, when some little things are added that come standard with other CMS (-- you already have HEAPS of extras) - this will be the BEST CMS by far! I can guarentee it!
(Having a bit of twiki style stuff would be good too... i'm guessing this is possible and i just haven't found this yet...)