I'll admit, I'm a Telegram newbie. I installed the app once, but kept finding myself drawn back to the standard Messenger (SMS) app. However, with the update to Telegram 3.9, I might get more use out of this popular (and secure) messenger app. You can finally edit messages, and it's easier to mention people regardless of whether or not they have a username.
Here is the Telegram v3.9.0 changelog.
Edit your messages everywhere within 2 days after posting.
Mention people in groups by typing @ and selecting them from the list — even if they don't have a username.
Get to your friends faster with the new People list in Search.
Find inline bot shortcuts in the attachment menu.
Add chat shortcuts to home screen.
Telegram v3.9.0 brings a few changes to the fore, including message editing. With a simple tap of your message, you can edit sent messages up to 2 (yes, count 'em, 2!) days after sending. Edited messages are marked with a simple 'edited' tag, so everyone knows you've changed your original message after the fact.
Telegram is also promoting their new mentions system and people list. The former allows you to mention any member of a group and sends them a notification, even if they've muted the conversation, while the latter helps you find your desired contact faster. As for the bot attachments, simply access the attachment menu and you will see your most frequently used bots alongside your other attachment options.