You become benevolent. You don't have "benevolent intentions." Your decisions would reflect this belevolence.
That doesn't sound like a good thing, to me.
But wouldn't that cause paradoxes? First of all, what one considers belevolent, others might consider malicious. In the terrestrial realm, things like abortion and stem-cell research fall into that category. I'm sure there are other problems like that, too, that don't come to mind. But the point is, what happens when one person considers an action good, while another considers it bad? Do they hold a vote, or does one person suffer?
Additionally, you can offend somebody by accident while talking to somebody. Like, you can mention that they appear to have gained weight, with the intention of saving their health, but it may offend the person. Again, there are tons of examples, look at pretty much any conversation with women.
What about humor? The most common (and often considered 'best') jokes are ones that make fun of a person or a group of people. That's why comedians do 'roasts' and why a lot of people avoid sitting at the front of a comedy club.
If it is indeed true that we are changed in this way, then I suspect we're living our lives wrong. I mean, why do we spend all our time in this world working and trying to better ourselves? I mean, the more logical thing to do would be to find some drug that makes you happy and benevolant, and make sure that everybody in the world takes it. I mean, that's pretty much what happens in heaven, so why not simulate it on Earth? (I'm sort of referring to Brave New World here).