I give this a 1 1/2 star simply for one scene: the hero's girlfriend takes a pill in the second act and 'thinks' her way out of the situation. This scene alone is worth the price of admission. Brilliantly written, filmed and edited. Unfortunately, it comes so late in the movie that it's almost impossible to care. The rest of the film is over-shadowed by this singular scene...
I rented this dvd to watch after I read the reviews for Lucy, another film with a similar plot. However with Limitless, I found myself incredibly bored from the beginning and had to pause it, and do something else. I went back again to try and finish it again...and again...and again. I did my best to not watch it on fast forward, which is the death knell for movies that I rent or stream. It took every bit of my 24 hour rental to get through this thing. I can't say I speak for everyone, but a movie experience should be a fun occasion, not a struggling ordeal.
Watch Lucy instead. That is another flawed film but it succeeds where Limitless fails: Lucy is at the very least funny, unintentionally so. I laughed my ass off watching Lucy, but Limitless gave my eyes a workout...they were either constantly rolling or watching the clock hoping it would all be over soon.
B) If the possibilities of what he could achieve with the drug were limitless, why didn't he just learn the chemical make-up and make his own so the situation never escalated? Clearly he wasn't that smart.
Even De Niro can't save this...