Haven't played Halo, so I can't really comment. 
So far

Chirix: Strong, dexterous, exceptional team-workers; herd mentality, panicky, overly emotional
Gorrompek: Fast, agile, rapid reaction times, fairly robust; overly aggressive, overzealous, tendency to act before thinking
Eliazoph: Extremely intelligent, the cleverest often working at scales beyond human capability; not very practical, physically inferior to humans, often absent-minded, sometimes overly logical, rarely decisive.