My wife and I spent the last 4 days of our Costa Rican trip in Tamarindo. This was our first visit to Costa Rica and I booked the majority of our trip using advice available on Trip Advisor.
We can support the positive experiences that others reported for this hotel. The Arco Iris is as advertised - lovely compact grounds, private quiet pool area, very nice cabins that are clean and cool, functioning A/C, very nice people.
Richard and his associates took care of some travel issues for us including booking a different hotel for us in San Jose. It was a relief to be able to rely on local knowledge to solve some issues.
The hotel is not on the beach but is a 10 minute stroll away. All along the road are restaurants, snack shops, stores, etc. so it is a very nice and safe stroll. Some of the highest rated restaurants are not on the beach but are within a five minute walk on or just off of that same road.
One note is that currently there is construction next door but hopefully the construction will be complete within the next few weeks.
All in all we are very satisfied with our choice.