Let me preface this by saying I am not a programmer, but I do know a few things about community management and have several here - public and private.
One thing I have always noticed about communities is how useless the member directory is. Every community has one of these - on this community just go to the "see all" member link. Even with just a few thousand members, it is already impossible to scroll through all of them - even if you could tell anything about these members through their pictures or hovercards. When you go to the search function you learn that the only thing you can search on is the users name - which is all but worthless.
If you already know the person's name you don't need to do a search for their profile - you could just go to it directly - that is not something you need to search for on communities. For business, it is much more likely that you would want to search for things like location, interests, industry and interests - and if those things aren't overtly stated in the profile, then at least a full keyword search.
As I have a business community that just hit 50,000 members, I have known for some time that i would need to dig into the API for communities. Like I said, I am not a programmer but I always assumed was at the very least i would be able to download a Cdl file of my membership data - but I hoped there were some cool things I could do beyond that.
Since i couldn't understand the attached API instructions, I asked a programmer friend of mine from here to look into it, but he seemed to already be familiar with the issue and said that the API had almost no useful functionality, and that Google didn't want us to have information about our members.
He is the only one I have asked so far, but rather than ask around covertly I thought I would just mention this issue here since this community is about using Google in business. Could someone let me know - what if anything can we do with that Communities Api and is there some way to get access to our members data for communities?