While picture and video quality will be better and it will have read receipts and typing indicators, it will still lack basically most rich message features in iMessage. Adding a non-Apple user to your group chat will continue to make the experience worse overall and will be avoided.

Want to edit or unsend a message? Want to send an Apple Music link or Apple Pay request? Want to join in a quick Group FaceTime? Want to share locations, even temporarily or long term? Want to use the new italics and bold type faces announced today at WWDC? Want to use the Apple Intelligence features announced today?

All will be restricted or worsened if you are stuck outside of iMessage.

But yes, pictures and video will be better quality.