P2 recently released two crackle polishes and I *had* to have them. There are only two colors (so far) and I hope that they're going to release new colors because unfortunatly the Isadora ones are quite expensive compared to P2( ~2€ vs 9€ or ~2,6$ vs ~11,7$).
I first layered them over my excisting manicure (Orly Wild Wisteria& Prisma Gloss Silver).
The effect isn't very obvious my nails except my pinky and sadly, the BYS didn't crack like the others, it had a cracked surface but the base-color wasn't shining through and my nail remained black.
Now, let's see how the colors look over a lighter base color, in this case P2 elegant (a 2 coater).
To me, P2 and Isadora look the same, tough the crackle-pattern varies how thick/thin you paint it. I tried to paint about the same amount of polish on all nails but due to the different brushes* it was quite hard.You can also see the pattern of the BYS crackle polishes I described before: they have a crackle-like surface but the base-color doesn't peek through. It's quite unique and I've never seen such a pattern before.
*P2 and BYS had quite skinny/average sized brushes, whereas Isadora had a wide brush about the same size of the OPI Pro Wide only a bit more brush-hair.
All in all I like the P2 crackling polishes. Due to the price they are definitly a steal and I really hope P2 comes out with more colors.