Groups have one very practical issue on nostr:npub1exv22uulqnmlluszc4yk92jhs2e5ajcs6mu3t00a6avzjcalj9csm7d828 that each message is basically sent as a DM to all other people, because of how delivery works on SimpleX.

If you were a message to a group with X people, you send X messages. If the message is a photo, you do the math. 

Also the user experience is not superb with groups, there are glitches. But it's getting better. Doing this right is surprisingly difficult.