If you look at his previous company VK. It is by far a superior experience to Facebook, given how intuitive, fast and sleek it is. Images load 3 times as fast and has many features which FB does not have. I use daily to keep in touch with my friends in Belarus, Ukraine and Russian. I only wish more of my friends used it. He has an incredible eye for design and product.
When people refer to VK being a clone of Facebook. This is innovation. Did Facebook invent the idea of Social Networking? It must be extremely annoying to be constantly referred to as "Russia’s Mark Zuckerberg" and having VK being constantly compared to FB.
Here he has had a brilliant opportunity for a fresh start, freedom to create something better than before and I'm sure he will take advantage of it.
As Steve Jobs put it. "Getting fired from Apple was the best thing that could have ever happened to me. The heaviness of being successful was replaced by the lightness of being a beginner again, less sure about everything. It freed me to enter one of the most creative periods of my life." Steve Jobs, 2005"
Everyone should look forward for what is to come with Telegram. There is some really great technological innovations going on. They've invented a new protocol(https://core.telegram.org/techfaq) and have a great API to utilise this technology(https://core.telegram.org/).
I'm sure you'll like it. Check it out: http://www.telegram.org