I think maybe your idea of “fine” differs from mine. It is a much worse experience than iMessage.

1. No threading is supported. If you reply, it duplicates the message being replied to.

2. “Tapbacks” (reactions) duplicate the message being reacted to with “so-and-so likes message … message”

3. Photos are reduced to a size that fits in MMS (very low quality)

4. Videos look like postage stamps

5. The chat cannot be renamed or have a photo added

6. Members cannot be added or removed without starting a new group (conversation)

7. No message effects

There may be others, but this is off the top of my head.