I'm talking about their recently released light blue creme shade; I Believe In Manicures (part of a Audrey Hepburn quote*), which is one of the polishes in the Holiday 2016 Breakfast At Tiffany's Collection. It can still be found almost-anywhere that sells OPI polish, which makes it a great comparison for people looking for What's With The Cattitude.
Read on for side by side swatches, read which shade I think is the better one, and to see how the formulas compare.
The side by side shots say it all - I don't think you need both of these polishes as the shades are extremely close. The only real difference between these light-but-bright blue cremes is in the undertones of the shades, which is only really noticeable out of the bottle; I Believe In Manicures just has a teensy bit of a minty undertone, while What's With The Cattitude has a plain white one [I'm not sure the camera picked up on the slight difference properly - the light-but-bright blue tones are vibrant and freaked it out].
The formulas for both shades are the same; the first coat applies streaky, so you'll need three coats to level it out. Cremes which need more than two coats to level out are usually fails for me, however lighter shades have a strong white undertone so I'm prepared to go for three coats with them for an even finish. The third coat gets rid of all the unevenness, and the formula is fast-drying, so going up to three coats isn't a big deal.
I think that these types of blues are cheerful all-seasons shades - refreshing in spring/summer, and icy in autumn/winter. The fact that neither polish stains, and that they both wear fantastically well is a huge plus. Also; I love OPI's pro-wide brushes - makes application smooth & easy, and the width fits my nail shape better than any other brand.
I do enjoy wearing What's With The Cattitude, but I prefer I Believe In Manicures - the mint undertones makes it pop more and adds uniqueness to the shade. If you do find What's With The Cattitude cheaply then it is worth getting as it has a nice formula for a pastel, but no, I think that it's not quite as 'wow' when compared to I Believe In Manicures.