Yes, I would and in fact we have several times! Three were in Cuba and one was in the Mayan Riviera. Mexico seems to handle newly opened resorts better than Cuba!
Whether it works for you depends a lot on your personally and tolerance level. The reason the price is good is because the resort amenities are usually not all completed. For us, having fewer a la cartes, an incomplete fitness centre, etc is not a big deal but then these things are not a vacation deal breaker. For you and your family though, would not having a finished Kid’s Club be an issue?
I do like the "newness" factor. Sleeping on a brand new mattress with new linens, first guests to use the room, etc. Important stuff like hot water, working AC were not a problem as everything worked. We also appreciated the fact that the new resorts we stayed at were at lower capacity, so no towel wars or other annoyances like loud music at the beach or pool (sound system was incomplete!). On the downside, the staff were still in the training phase and not everyone was up to snuff as to where supplies were kept or with the speed of service but we weren’t in a big hurry anyways.
There was some ongoing "finishing" construction- it one case a tad bothersome in the other cases not at all so that can be hit & miss. Changing rooms is sometimes more difficult because the whole resort may not be open yet. Our experience has been that they try to get the more premium rooms done first so although we booked a basic room (lowest cost) we ended up getting an "upgrade" as a bonus.
I would definitely take the "risk"- in fact think I’ll go check out the info on this new Villa del Palmar right now! Of course there’s nothing wrong with "tried & true" but unless there is a very specific reason for us to go back to a resort multiple times – think good snorkeling in our case- I find it gets quite boring going only to one resort in one location all the time.
Have fun with your research!