I decided to do Honolulu as part of my 50 states quest and a vacation celebration of 25 years of marriage. We stayed at the military hotel, so we were able to get a break in the price and stay out of some of the madness. Approximately 30000 registered for the race but only 22009 showed up to run and many of those were Japanese runners treating this as a destination marathon. The pros and cons were:
Pros
1. Lots of support on the course
2. Frequent water stops with water, Gatorade, sponges, and PowerGel.
3. Fireworks at start
4. No time limit
5. Nice medal and finisher tech shirt
6. Well prepared medical staff
Cons
1. Lame small expo with many booths having little running connection
2. No easy transportation to start or from finish
3. Bags with clothing needed to be checked day before race at finish line
4. Out and back 10 miles of course on highway with no shade that compounded high temp and high humidity weather that is common for the marathon
5. Insufficient portapotties and placed too close to start
6. Pace signs at start, but no corrals so many runners did not line up appropriately
7. Sold as destination run to many Japanese runners many of whom were not adequately prepared
8. Finish line poorly arranged forcing runners to walk long distances to claim medal, finisher shirt, and post race food.
9. Registration was over $150 unless you registered in the first few weeks or were a local

I recommend considering a marathon on one of the other islands or coming into Honolulu with significantly reduced expectations.