I've tried a host of different phones and tables with the ring now. none of them do very well.
With my phone its still rather hard to read. I find that the ring has to be perfectly flat against the phone to read. I also have to leave it there a while before it picks up. It seems to help if i slowly move it left or right on the sweetspot if it hasn't picked up after about 3 seconds. If the ring is tilted in any way it doesn't read at all.
Ironically the larger tag is the hardest for any of the phones i've tried to read. The smaller tag picks up easier, which is not something i expected.
It seems that when i power cycle the phone it picks up the ring easier when it's presented right after the power cycle. Maybe this is just some kind of placebo or psychosomatic/magical thinking. It just seems like the ring can be held a bit farther away and at an angle for that first read right after the power cycle. Maybe there is some kind of power saving feature that android kicks in a few seconds after reboot that turns down the power to the nfc antenna. Maybe this power saving feature it's not in effect for a few seconds after reboot. Maybe, i'm just crazy...
I really need to order an alpha ring to see if that will read better. After trying this ring with all the devices i have i will bet that an alpha ring will be the best choice for most people.