Advantages: Good interaction with the community. It is even possible to solve grammar issues which mostly isn't possible with doing a language exchange only. The question section is quite good for this purpose. The notebook section is, wisely used, also a good place (but I usually don't know what to write about, so I actually only have written 3 entries so far xD).

Disadvantages: The private messages usually have a limit which for me as a jabberer is a little bit inconvinient. But what I would want to see be changed even more is: why can't we highlight and mark things in our private messages? :( This would be so useful in order to correct each others mistakes.

To me, the chief value of italki is in finding paid teachers willing to give me individual lessons via Skype at reasonable prices, and in finding language partners willing to chat with me via Skype at no cost.

I find the "community" aspects of italki to be limited. Helpful, but limited. You certainly can't learn a language just by hanging out here on the site and exchanging online text messages, and there are no computer-based language teaching tools here.

What I like most on italki is the notebook feature, because it gives me the possibility to get corrections of my texts. In addition, I like it to look at other student's entries to learn more about them. It is helpful for me to find interesting people.
What I miss is something like a "moderated chat". I mean one teacher prepares and moderates a lesson for 3-5 students at once. This would not only reduce cost per student, but would also give you a chance to meet other students with similar interests. Organising such a thing without a teacher is probably to chaotic...

I am sorry Learner, I can not contribute to this discussion because I am new here.