The count of notification gets erased after we view just one of the many notification. There is no easy way to identify which of the many notifications we have viewed, i.e., if 5 people have responded to 5 different posts and I only have time to read one of them, i can't determine which ones i have not read. Yammer get track of this process quite nicely.
Please go get some of the Yammer dev team members as consulants for the UI in this network.
Also, please separate the Likes, Mentions and Response, having them all in one big long list is confusing and makes it hard to focus on the replies.