Decreased stress and anxiety
Increased focus
Increased mindfulness (the ability to be aware of what's occurring at any given moment, but being able to choose how to act, as opposed to just reacting)"
Are those three benefits purely anecdotal?
Here are some cursory studies addressing your three questions. They are easy to find on Google Scholar.
Decreased stress and anxiety http://online.liebertpub.com/doi/abs/10.1089/acm.2010.0142
Increased Focus (specifically for people on the ADHD spectrum) http://www.ahc.umn.edu/img/assets/20825/MindfulnessADHD-Zylo...
I have to imagine mindfulness is a difficult concept to disentangle from meditation itself, however there do seem to be attempts to create measures for this: http://journals.sagepub.com/doi/pdf/10.1177/1073191107313003
Here's a meta-analysis summarizing many studies about the effects of meditation. Effect sizes seem consistently positive albeit on the smaller side: http://link.springer.com/article/10.1007/s12671-012-0101-x