I will attempt a comparison between the shaman types described in the PF APG and the regular Druid.
First up, the Bear Shaman
Level 1: Advantage Druid. The Shaman must choose a Bear companion or from a smaller list of Domains. In return, he gets a conditional +4 bonus to Wild Empathy.
Level 2: Advantage: Shaman. The Shaman gets Totem Transformation, a neat utility or combat boost for one encounter.
Level 3: Advantage: Shaman. Two uses of Totem Transformation. Also, the shaman can take Multiattack or Improved Natural Attack ahead of the Druid.
Level 4: Advantage: Druid. He gets Wild Shape, the Shaman doesn't.
Level 5: Advantage: Druid. The Shaman can summon a young grizzly bear as a standard action with SNA III. The young bear has about twice the HP of other summons and the best AC and Grapple, and is a contender for best fighter all-round. But the Druid has Wild Shape 2/day.
Level 6: Advantage: Shaman. 3 uses of Wildshape per day to the Druids 2, although 2 of them has to be bear form. A Large or Huge bear is a decent combat form, the Shaman uses Beast Shape III, and has enough uses to be in bear form all day, even if he switches to a utility form for one encounter and then shapes back to bear.
Level 7: Advantage: Shaman. The Grizzly Bear, even with +7 Hp, is not a clear winner for SNA IV, but: Standard action to summon is still very, very nice.
Level 8: Tie. The Druid gets Elemental Body II and Plant Body I, none of which really do anything for him. The Shaman gets Elemental Body I for utility. The Druid finally gets Beast Shape III. The Shaman has more uses.
Level 9: Druid. Young Dire bear or Advanced/Giant Grizzly bear are not great contenders for SNA V. Venom Immunity is better than a bonus feat.
Level 10: Advantage: Druid. Elemental Body III is very nice.
Level 11: Tie. The shaman can still summon a second-rate animal with a standard action, but meh. Dire Tiger beats Dire Bear hands down.
Level 12: Druid. Elemental Form IV.
Level 13: Druid. Venom Immunity and a Thousand Faces vs. Totem transformation and two bonus feats.
Level 14: Shaman. Full wildshape now, and more uses per day.
Level 17: Shaman gets another feat.
Conclusion: Shaman is pretty sweet from level 2-4 and 5-8. The star abilities are the standard action SNA and the faster access to large/huge Wild Shape forms. He loses out a bit in versatility, and his advantages become inconsequential at high levels.