Hi Cadge,
I have stayed at the Touareg twice since its opening in 2011, once in the Adults section and once in the main section.
As to the worth of upgrading there are a few points to consider, the adults section is as stated for adults only, you will have your own swimming pool and totally kids free, there is no swim up bar if that's what you want, you will have to get out of the pool and walk a very short distance to the adjacent pool bar...not such a bad thing, my only gripe is that there are fewer loungers around the pool that guests, seating by the pool bar, again limited, despite rules saying that reserving beds is a no no, it happens, in other words if you don't take up your chill position by 08:45-09:00 you may miss out.....options then are to grab a place on the beach, can be an issue due to it being windy and a long way from nearest bar and beach not adults only (if that's an issue), or finding a lounger by the main pools, defeats the object of adults only upgrade.
Other benefits include the exclusive use of the bar facilities by the adults pool for pre evening meal drinks and an exclusive use of a gourmet restaurant., be aware that this adults only restaurant has to be pre booked and has limited choice, and if you think you can eat there at any time then think again....too small a restaurant for the demand.

Hope this helps and it is just up to your needs, if you have further Q's pm me.

Regards

Joe