As a new Mastodon user coming from Twitter, here is what I find most user-unfriendly.
1. Layout which doesn’t distinguish between original post and a reply to it. Very confusing.
2. Can’t figure out how to read a thread in sequence. Maybe my fault?

Twitter screenshot for comparison.
Maybe incorporate a few of the good design features of Twitter here? They didn’t get everything wrong!

Thanks to all for the suggestions! I’m trying Metatext and I like the layout better than with the Mastodon app.
I also tried Twidere but wasn’t able to display my own thread properly with that, and also it crashed twice.
I was attracted by the feature to post simultaneously to Mastodon and Twitter with Twidere though - are there any better iPhone apps out there able to do this?
@rahmstorf you can set automatic cross-posting from mastodon to Twitter (or viceversa) with some options using this website: https://crossposter.masto.donte.com.br/
Mastodon Twitter Crossposter

@rahmstorf my two cents: I set up this cross posting service and then decided it was best to try mastodon without it to learn about the community here. So I stopped cross-posting. I haven’t regretted it.
@carlosmoffat @rahmstorf I was using moa.party to cross post from Mastodon to Twitter (not the other way, I think that makes it harder to meet the Mastodon community), but turned it off last night as I’m more or less giving up on Twitter