Same with me. I just switched from iPhone to droid and now i cannot group text in some situations. I got textra at a friend's recommendation and did not solve the problem. I can text with SOME iphone users in groups, for example:
- group with one iPhone user, two android users, and me (droid user) - this works
- group with four iPhone users - they can see my texts but i cannot see their replies
- group with two iPhone users - i only receive some of their texts, i think they can see everything i write

I heard that you have to be the one to start the group text with iPhone users, but I initiated the group text with my four iPhone friends when i got my new droid, and still not working. wondering if they mean you have to be the one to start the group text from the very get go (years ago)

driving me nuts and i have to decide if i should go back to verizon and switch back to iphone :( i love the droid but this might be a dealbreaker if i cannot group text my friends!! hoping textra has the magical solution....

I am having the same issue on my Samsung & Edge no matter what text app I am using. One issue I found today was friends on iPhone are suing IM common messaging app. Once they have disabled IM, do see their text. But that's not a great solution since they are reluctant to disable their im.