Yes it works. As warjo1 wrote before me, you just need to add the correct APN.
I got my Atrix 2 and experienced the very same issue, only voice and sms worked out the box. While in the store, the guy at the front desk, provided a new sim card, didn't worked. He called another guy, this guy said: LTE wont work on prepaid yet. I told him: This phone is not LTE is just HSPA+, he said, 4g is only LTE, so your Atrix 2 is LTE. After that affirmation, I said: OK man, thanks, bye!, walked 4 steps outside the store, went to access points, added the one I remembered from my old phone and voila!!!!
It is just amazing how the ATT Reps know nothing about the phones they sell.
The very same day I went to a Verizon store to play with the Droid Razr, it was amazin how the guy knew everything about that phone and also about mine...
better reps at verizon? probably!!