If you're asking whether or not people use live chat services in general, and whether or not they are effective, then the answer is absolutely. Otherwise you wouldn't see this feature offered on so many high profile sites - especially online stores where people may have questions about products or shipping, etc...
Personally, with Mibew it seems like my customers have had a good experience chatting and with the application. There have been no complaints.
Hope that answered your question in some capacity.