Any recent reviews of this property? Thanks!

Look at tripadvisor.com.
The JW Marriott is widely regarded as one of the top 3 hotels in Cancun.
(The others being the Ritz Carlton and the Fiesta Americana Grand Coral Beach.)

stayed at the Marriott Casa Magna which is next door it was a great hotel liked
the Fiesta Americana Grand Coral Beach better. The sea was much calmer there. Hardly any waves. Hotel was the best!!!!! Highly recommend it.

Just as an fyi, the JW Marriott and the Casa Magna Marriott are two different hotels in case you did not know.

I thought they were the same corporations differenet names, my mistake

The JW Marriott and the Marriott Casa Magna are part of the same chain but totally different hotels. The JW Marriott's are always the most upscale of the Marriott chain.
In recent surveys of the worlds best hotels, I have seen only the JW Marriott and the Ritz Cancun listed as the best in the Cancun area.