Functionality of a site is the implementation of features.
For instance, feature: List all the posts that I have made. The way that all of the posts are presented and the options that come with the listings is the functionality of that feature. PF.com did this better. Sure, you can argue that "the options that come with the listings" points to features that were available on the old site that are not available on this site, but that is not how I am viewing it. The way I view it is that this site presents information a certain way and the old site a different way. The old site did a better job of presenting information (like my posts).
When I look up "functionality" in Google, the definition is "capable of serving a purpose well". This site seems less capable of serving certain purposes than the old site.
Does that sufficiently answer your questions?
As to the complaining, If I cook a bad dinner for my son, I expect him to tell me that it is not a good dinner, I don't expect him to sit idle and keep his mouth shut. If he tells me that the dinner is bad, he is not complaining, he is giving his opinion on my dinner. Likewise, I think this site fails to serve it's constituents as well as the old site did. I stated my opinion about the site. I'm sorry you see that as complaining.
I think that Robert did a grand thing by saving this forum and migrating users and old posts. However, just because he did some nice or considerate things by saving the information from the old forum, that doesn't mean that this forum is a better forum. To Robert, thanks for all you have done to save the old forum. I truely mean that. Philosophyforum.com is important to some peoples philosophical development, at one time I was one of those people. Of late it has fallen out of favor in my life and that occured long before any merger.