The Collaborative International Dictionary of English v.0.48:

ambivalent \ambivalent\ adj.
   1. 1 undecided as to whether or not to take a proposed course
      of action; having feelings both for and against the
      proposed action.

   Syn: on the fence(predicate), suspensive, uncertain
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

ambivalent
    adj 1: uncertain or unable to decide about what course to
           follow; "was ambivalent about having children"

Moby Thesaurus II by Grady Ward, 1.0:

66 Moby Thesaurus words for "ambivalent":
   amalgamated, ambiguous, ambitendent, amphibious, antinomic,
   at loose ends, blended, capricious, changeable, combined, complex,
   composite, compound, compounded, conflict, conglomerate,
   contrasting, dappled, double-minded, dubious, eclectic, equivocal,
   fence-sitting, fence-straddling, fickle, fifty-fifty, fluctuate,
   half-and-half, heterogeneous, indecisive, indiscriminate,
   infirm of purpose, intricate, ironic, irresolute, irresolved,
   jumbled, many-sided, medley, mercurial, mingled, miscellaneous,
   mixed, motley, mugwumpian, mugwumpish, multifaceted, multinational,
   multiracial, mutable, of two minds, oxymoronic, paradoxical,
   patchy, pluralistic, promiscuous, scrambled, self-contradictory,
   syncretic, thrown together, uncertain, undecided, undetermined,
   unresolved, unsettled, varied