I found Willdial's user guide to be very clear - so long as you follow his instructions, you'll get Genesis 3 and the bulk of its product line working in Poser just fine. Shoes can sometimes be a problem but most will work fine if you apply any included foot pose before adding them to the scene. There are some clothes that won't work and I'm afraid that most of the hair items won't work either, so it's better to re-fit older hairs.

If anyone is interested, I have a thread over on the DAZ Poser forums listing all the products that I've tested and the results - it could help you choosing what to buy and saving money on what doesn't work. I haven't had time to test everything that I've purchased yet but I think there's a long enough list to be useful (I would reproduce the list here but it's in a table which I don't think these forums support)..