I have been using it quite a bit and even gave the paid version a go.
Pros:
It makes keeping up with DMs, groups, and channels a lot easier. It let's you have more flexibility in organizing things and gives a more familiar UI like you would expect from Slack, Discord, or other similar UIs. They update it constantly. Very active devs.
Cons:
Mostly that it doesn't have feature parity with the actual Telegram client. However this is a temporary con, I now. I really can't think of any cons that aren't temporary. Also the missing features are very minor ones like file type support, access to your stickers and Gifs is not as expected.
Telegram should stop messing around and back these guys directly. This type of UI is practically a standard now. Thanks Telefuel. keep up the great work.
PS. When wallet and Dapp integration?😉