Prep + Prime Beauty Balm is lightly tinted in a nearly sheer beige tone to work on an array of complexions, it creamily re-texturizes the skin and then goes on to excel at being a face primer with highly everyday UVA/UVB SPF defense.
A BB cream is somewhat what this product is supposed to be. From my understandings, BB stands for blemish balm, and what it is supposed to be is a multi-tasking cream that takes care of everything: skincare, sun protection, and skin tone evening. Most of them have high SPF and usually have the "special" sunscreens that protect against both UVA and UVB rays, which is an important factor with sunscreen. Most of them also have special skin treatments like anti-aging ingredients, and also whitening ingredients. Another thing is that these are supposed to be like a sheer alternative to foundation. I would say that the coverage is supposed to be a few notches more than a tinted moisturizer. I personally own the Missha Perfect Cover BB Cream. I'll review that later. I like certain things about it, but there are some things that make me not like to use them.
Anyway, my point is, I don't think MAC's intention was to make a BB cream. I think if that is what they intended, they would have done a few things a little different: 1-they wouldn't have called it a beauty balm versus a blemish balm (what BB is supposed to stand for), 2-I think they wouldn't have put it in the Prep + Prime line, and 3-they would have made a few more shades. I know traditionally, BB creams don't come in the largest array of colors, but it's MAC, they're usually skin tone accommodating. Well, I just wanted to point this out because many of the reviews I've been reading about this product compare it to BB creams. I really wouldn't. I actually would put this product into just a skin tone evening primer, with a sunscreen.
In the end, I think this is an interesting product. I think good for the summer in that it could even out your skin tone prior to foundation so that you don't have to wear too heavy of a foundation. Plus you have a rather high SPF, which is always great to have. I don't know if this is going to be in the permanent line, but if it is, I may look into buying it one day.