To be clear, we didnt stay at the Modern but enjoyed the pool-pool area as rentors at the adjacent Ilikai Towers.
The best thing this hotel has going for it are its amenities: the pool area, the restaurant (Morimoto), and the downstairs lounge (the Study).
While you cannot technically use the pool or the rent a chair during the day, you are welcome to sit and order some food/drinks by the poolside bar. This is especially enjoyable in the evenings - the whole deck are is so well decorated and even includes cut off wine bottle lights hanging from the trees. The food is good (especially by Hawaiian standards which are a far cry from the quality of food we tend to be accustomed to in Vancouver, Canada) and the drinks are fine although if you want the best cocktails on the strip you have to stop in at the Moana Surfrider. With few people in the pool, the staff was nice enough to let us swim both times we went for an evening drink/meal - they even provided us towels.
No question this is the nicest pool area in Waikiki - well worth an evening stroll to visit