What are its design problems?
- all useful interactions are hidden behind useless slow animation and multiple additional clicks
- photo selection is an awkward double scroll
- stickers are tied to external apps, cannot be searched, take ages to load when you switch between sets
- link unfurling and file previews are hit and miss, often take ages to happen
- pinned chats are useless awkward circles that take up space instead of being actual pinned chats
- continuously broken on MacOS (photo selections, unread status synchronizations, keyboard shortcuts etc.)
And it's a key app they have on two platforms.
Compare that to Telegram which exists on 5 platforms and web, developed by just a handful of people, and has everything and more.
Maybe this is why I prefer it. Text is first class on iMessage.
WhatsApp and Telegram messages tend to have crud, e.g. stickers and weird shit happening with photos. To each their own.
But when you need to, it's there at your fingertips, not hidden behind laggy animations, seconds of loading, and awkward interactions
I don't care much for its stickers but it has a ton of quality of life features. Group chats with topics. Built in translation. Fully supported bots that can add tons of functionality. Voice message transcription. Full access to everything on the web. No problems with bridges (eg to matrix). I'm happily paying the premium fee too which is only 30€ a year. It provides even more quality of life stuff like fully automatic translations (my Spanish isn't the best yet)
Here in Spain it's used a lot especially for groups. WhatsApp is still #1 for 1:1 chats but all the groups (eg associations) i know use telegram.