A2 steel is well known in boutique tools. As O1 steel was a more alloyed version of prior steels allowing it to be hardened more slowly and still be fully hard, A2 is an extension further with Chromium and Molybdenum added in significant amounts so that the steel will attain full hardness when quenched in compressed air.
A2 tends to have a fairly specific hardness range if heat treated properly, and will end up 61-63 hardness. The nature of it lends it to be improved further by cryogenic treatment (a soak in liquid nitrogen) trading hardness for toughness. Put differently, cryogenic treatment makes the final product a little harder, but if you use your chisels like crowbars, they would break a little bit more easily.
Edge life for A2 at the same hardness as O1 is about 25% longer, with sharpening in most media a little bit more effort than 25% more. Sharpening should be done with stones that will cut chromium carbides, which is pretty much all synthetic sharpening media. Natural oilstones will not sharpen the steel properly leading to the semi-myth that A2 doesn’t get as sharp. It does if the sharpening media can cut through all parts of it.
Edge uniformity isn’t as good as O1, but the steel is much easier to heat treat industrially even than O1 and moves little and doesn’t change hardness much if a tempering oven is uneven. This makes it an ideal steel to use for modern manufacturers, as heat treatment issues are solved by ease of use rather than skill. And the trade off is one that most new amateurs won’t care about. Experienced workers are less likely to have a preference for it.
In a world where some heat treaters are discontinuing steels that require a fast quench, A2 will remain common and O1 less so (recall recent mentions from Ron Hock that his heat treater quit, and Lie Nielsen advising that they stopped offering O1 because they lost the the heat treatment option for it).
A2 needs a soak at a higher temperature to be done right, so it’s more suited to commercial inert atmosphere furnaces than home use, where it would need to be coated or wrapped in hand-cutting stainless wrap.
It’s my opinion that we see A2 in use mostly because it solved problems for the manufacturers and not woodworkers.
While it can be sharpened as finely with hard abrasives, the wear at the edge tends to be less uniform than O1 or even plainer steels (vintage laminated irons or W1 or W2, for example) and the late wear stages before sharpening can be ratty.
Most of the commentary about practical edge gains come from comparing A2 steels to O1 that aren’t hardened to the same hardness.
Of Making by Hand with Wood and Steel 