The JPX ball is a new development for Mizuno as it fits into their mid-handicapper player range that the JPX woods and irons are a successful part of.
This is generally focussed on distance performance first and the ball is not different as the 3 piece low spin design aims to launch it high and let it fly.
It will have to come down eventually and Mizuno has spent a lot of time working on the descent and the micro-dimples in between the major ones are there to slow the descent and keep it in the air longer for more distance.
The larger dimples give the lift at launch and the smaller ones take over as it slows down at the peak of its trajectory and starts to return to earth. This means that there are 512 dimples in all, which is the most I can remember seeing on a ball and it gives a unique look at address.
If you are an even-keeled type of guy then you may be at odds with the Mizuno numbering as they use 1, 3, 5 and 7 in each dozen box.
When I was testing the JPX next to the Mizuno MP golf balls it was noticeable how much louder it was with a driver and this is a result of that firmer feel.
It wasn't ear-splitting, but it was noticeable, with a more clicky sound on irons and around the green too. Even with plenty of loft in hand the JPX took a lot of persuasion to sit down, so this is a distance offering for those who need to get up to the hole rather than screw one back.
The distances were very similar to the MP balls, but it is how it gets there and will be player dependent. For me, the spin on Skytrak was around 200rpm higher than an MP-S ball with the driver and 5-iron and around the same as the MP-X with a full shot on a wedge.
The feel when putting is much firmer too, so I am not sure about the 'soft' rating Mizuno give it on the box. It reminded me more of a two piece ball of the past than a 'soft' performance ball of today.
And this is the issue with the JPX ball. There are many 'distance' balls in the market that may or may not go further, but they have a little more greenside control and cost less and in this sector, these things matter.