Got a case today and going off the ratios I got, I think that you get 4-6 ultra rares and 10-12 holos per booster box. Here is the list of what I got in each of my booster boxes just in case you're wondering:
Booster Box 1:
Deoxys Ex FA
Heatran Ex
Latios Ex
Juniper FA
Rock Guard
Ultra Ball Shiny
Booster Box 2:
Thundurus Ex
Latias Ex
Life Dew
Tornadus Ex
Booster Box 3:
Thundurus Ex FA
Deoxys Ex
Ghetsis FA
Juniper FA
Booster Box 4:
Latios Ex FA
Latios Ex FA
Ghetsis FA
Sigilyph Shiny
Ultra Ball Shiny
Booster Box 5:
Thundurus Ex
Deoxys Ex
Rock Guard
Juniper FA
Life Dew
Empoleon Shiny
Booster Box 6:
Ghetsis FA
Heatran Ex FA
Latias Ex
Sigilyph Shiny
Max Potion Shiny
Trust me, I didn't misspell Latias for Booster Box 4, I truly got 2 Latios Ex FA. Other than than, I was fairly happy with my case, so I can't complain, but these ratios are way more crazy than Dragons Exalted, maybe because there were 10 more ultra rares this time. Well I hope this helps.