Emotiv offers two versions of the headset shown in the TED talk: the EEG (which allows users to access their raw EEG data) and the EPOC (it costs much less because which only allows you to run applications and doesn't give you access to the raw data). Because I only had a causal interest in the topic, I bought the EPOC headset.
I tested the EPOC headset on myself as well as a few friends. When my friends and I first saw the Cognitiv Suite, the response was similar to the crowd of the TED talk: people were impressed that the virtual box would move after training the first action. However, the excitement faded after using the Cognitiv Suite for a few minutes and trying to control multiple actions because it isn't highly accurate at detecting a specific thought. For example, if you train "push" and "left", you will probably see the box move towards you more than it moves left (or vice versa), and the action probably won't really be in sync with your thoughts.
In short, I didn't find the EPOC headset to be as cool as I was hoping it would be because it wasn't a very effective tool for providing mind control. Nevertheless, I do think it is interesting to be able to visualize my brain activity (see the links to additional posts below).
Part #1: Review of EPOC Apps
Part #2: Tracking My Thoughts Using the Affectiv Suite
Finally, it may be worth noting that there are other devices with similar functionality (for example, see this list from Wikipedia), which is something that I didn't initially realize. The Emotiv headset may really be the best option, but I would at least recommend researching some other options if you were interested in trying out a "mind reading" device.