I have flown a few times on Aloha interisland. As others have stated, they use 737-200s exclusively on their interisland and Pacific Island (Midway, Marshall Islands, etc.) flights, with 737-700s used for the flights to Oakland, California. The 737-300s and 737-400s they used to have in service are now with other airlines.
Interisland inflight service is ok; you can't really expect much when the longest flight (Honolulu-Hilo) is around 200 miles, 35-45 minutes. Personally, I have found that Hawaiian has slightly wider seats and more legroom than Aloha. Generally I fly interisland on Hawaiian, because I am often connecting to/from Los Angeles and get the best deal with Hawaiian the whole way, compared to interisland on Hawaiian or Aloha, then to LAX on another airline.