I admit, when I first saw this Brush I was intrigued and thought it was kind of strange..it honestly does look like a toothbrush.. but after using it, I absolutely love it!
I purchased this brush a few months ago but kept it aside in its packaging for quite a while. I don't know why, I just ended up going back to my normal concealer and Blending brushes. Then one day I finally decided to just open the box and try it out! I don't think I'll be going back to my other concealer brushes now..
MAC's Oval 3 is a multi-purpose brush made with synthetic fibres and it's incredibly soft! It works so well with concealers (liquids/creams), it blends like a dream! It's also great for contouring your cheeks and nose and blending out eyeshadow (powders/creams), however, I prefer using normal Blending Brushes for my eyeshadow, I find it a little tricky and uncomfortable using this brush for my crease area, it just doesn't work as well as your typical blending brush. But that's just my opinion.
What I love most about the Oval 3 is that the bristles are so densely packed so the makeup just sits on top of it instead of sinking down to the bottom - no more makeup wastage! It also has a unique handle shape with a rubber grip, it's so much nicer to hold than the typical paint brush style handles.
This brush does take a bit of practice and time to get used to, but once you've mastered it you'll love it.