Regarding left and right the result from last time is interesting:
1st round
Mirlande Manigat, Rally of Progressive National Democrats (SoCon, Nationalist right wing) 31.4
Jude Célestin, Unity (Soft Left) 22.5
Michel "Sweet Mickey" Martelly, Peasant Response (Populist) 21.8
2nd round
Michel Martelly 67.6
Mirlande Manigat 31.7
Against all 0.7
Former first lady Profesor Mirlande Manigat topped the poll in the first round, but failed to increase at all in the second. Her and her late husband Leslie Manigats party (which seems to be one of the more "real" ones) is in a new alliance - but I have not been able to find out who they are backing.
After widespread rioting Celestin was pressured into not running in the second round by OAS (on rather questionable grounds) and Manigat failed to increase her share at all in a second round deemed generally fair.
Preval as president spent government money on Celestin (a relative unknown at the time)'s campaign, there was widespread reports of vote rigging, and I think Manigat and Martelly both refused to acknowledge Celestin finishing 2nd in the 1st round. Celestin agreed to back down at the OAS' urging.