Recs.
Updated
SpecsUpdate
Pros
Pro Private cloud storage
Everyone can easily upload self files to their online storage or clone other user sent files.
Keep it , manage it , share it , remove it. There is unlimited data storage - 2.0GB per file.
Pro Secure
Pro Save time with inline bots and link previews
Unfortunately, on the desktop videos don't play, but images are viewable without visiting popular websites like imgur and Instagram.
You can play YouTube videos and others within the app, so you don't need to embed code or anything.
With inline bots, such as @gif, @pic/bing, @vid/YouTube, etc, you can look things up without leaving the client or chat that you're in. Simply type the name and some keywords and wait for the results to load.
Pro Two-step verification
You can set up an additional password to your account, which can be reset by your email. You don't have to use an email if you do not want to. If you lose access to your email or forget your password, you will be able to reset it via text message if your account is over seven days old and will receive it within a week (in case you recover anything before then).
Pro Cloud chat keys are kept in different jurisdiction
Even though encryption used for cloud-based storage (e.g. Gmail, Facebook, iCloud) may not be as secure as end-to-end encryption or zero-knowledge storage, Telegram does the most that it can by holding keys to chats in different jurisdictions, requiring intergovernmental cooperation to obtain the keys. This is aside from whatever other security measures have been taken, of course.
Cons
Con Doesn't use proven encryption
Telegram uses their own proprietary encryption called MTProto. It was their own creation. It was competently created by mathematicians, but not encryption experts. It has not been proven secure.
Con Limited "Secret Chat"
Secret chat is only implemented in the mobile apps, meaning there is no way to encrypt messages end-to-end when using the desktop client or the web browser client.
Con Video messages
You can send small video messages just the way you send voice message.
Recommendations
Comments
Flagged Pros + Cons
Pro Group Voice Chat
This Discord-like feature adds to the interactivity of the application.
Pro Supergroups of up to 200,000 people
In Supergroups, anyone along with admins can delete their messages from all sides. All of the user's messages can be deleted by an administrator, and they can be banned and reported as well. Supergroups can have a public link (outside of Asia, due to high spam volumes), which is also a username.
Pro Pinned Messages
You can pin messages to the top of groups or supergroups so members will see them when opening the group.
Con "Secret Chat" feature is not available for desktop client
Secret chats with end to end encryption are only available on mobile apps.
Pro Group voice chat
This Discord-like feature adds to the interactivity of the application.
Pro Supergroups of up to 200,000 people
In Supergroups, anyone along with admins can delete their messages from all sides. A message can be pinned to the top. All of the user's messages can be deleted by an administrator, and they can be banned and reported as well. Supergroups can have a public link (outside of Asia, due to high spam volumes), which is also a username.