I've been using this brush mostly to apply my undereye concealer. As well as for cream blush. And to me, those are the two tasks that this brush really masters. Especially because I have a large undereye area that needs to be covered, plus I've been doing the 'triangle' technique with my concealer that works to conceal my undereye as well as highlighting the area on top on my cheeks. And this brush covers it in no time. The pointed tip makes drawing neat lines when creating the 'triangle' as well as reaching the inner part of my eyes much easier.
However, if you are thinking about purchasing Core Collection in the hope of getting a decent foundation brush, especially if this is going to be your first foundation brush, I'd suggest you to look for other foundation brush.
The brush case is sealed with velcro flaps so the brushes are securely stored which also makes it suitable for traveling.
If you are interested, Real Techniques Core Collection is available for $17.99