Firstly this review is long overdue as we had our wedding in April 2017 with 60 guests.  Employees/services may have changed since then but I'm writing this as the points below should still be valid.

Prior to the wedding I had travelled to Cancun / Playa Del Carmen about thirty times on vacation over a period of ten years staying at numerous hotels (this was because I lived 250 miles away in Belize and would drive there for long weekends).  We started looking for all inclusive hotels in the area about a year in advance.  Basically we researched every hotel between Cancun to Tulum, around 200 hotels in all.  Our criteria was wide:-

Price range of rooms had to be relatively affordable (as we were inviting guests on different budgets/expectations.  We were aiming at $175 max a night per person).

Had to be child friendly.

Overall condition of the hotel had to be good (we did not want to stay at dated, run down location).

Price of wedding.

Facilities, food, entertainment etc within the hotel.

Basically the hotels we liked the most were adult only.  In the end we narrowed it down to three hotels and chose the Moon Palace (which I hadn't previously stayed at).

Firstly one of the reasons people book destination weddings is the belief that it will save a ton of money over having it back at home.  The amount of money you will save will not be nearly as much as you expect.  Our wedding at Moon Palace cost about USD 25k for 60 guests (beach ceremony, 1 hour cocktail, 4 hour reception, food, photography/videography, makeup, decorations, DJ etc. Not including rooms/flights/outfits).  This was selecting low to medium range options and having it off season (high season is mid Dec to Easter).   We also looked at having the wedding in Northern California at venues such as Monterrey, Napa, etc.  I would estimate the cost of having the destination wedding was about 80 to 90% of the cost, so around 15% cheaper.  Don't expect it to come in half the price (like for like service).  You sign a contract with the all inclusive hotels and it is basically impossible to save money by doing/sourcing things outside yourself.  You have to use their photographer, DJ, decorator etc.  You can bring in your own but the additional charges added by the hotel take away pretty much any savings.  All the hotels offer discounts, usually based on the number of guests.  When you do the maths the discounts usually mean spending more/increasing number of guests to get the discount (we ended up paying for guests rooms just to get a discount, so didn't save that much in the end).  

Now I have got the fact that the savings won't be significant let me get to the wedding/hotel experience.

Hotel facilities were great, beach was fine, food was good, rooms were clean but a bit dated, staff overall worked very hard.  I won't go any further than this as there are plenty of reviews already of the hotel.

We arrived five days before the wedding.  I could tell our wedding planner worked hard with us.  We spent everyday beforehand with them.  Some of this was due to us learning.  There is some disorganization within the hotel though, more would be expected given how many weddings they perform.

Ceremony was on the beach, went well.  Cocktail reception outside went well.  However after the ceremony the photography (while very good) took longer than expected, then a 10 minute walk to it, followed by a ten minute walk afterwards.  It meant most people arrived at the reception 45 minutes late.  Only issue here is our reception now became just over 3 hours which really wasn't long enough.  Our coordinator did let us extend though, I think by 45 minutes (don't know if we were charged for that).  Positive is afterwards we just went to the hotel bar.  In summary don't skimp on the time at the reception, it will probably overrun.  Reception was indoors in a hall.  Our hall felt a bit empty with 60 guests and bland as we didn't spend the extra thousands on drapes and stuff.

Overall we liked the Moon Palace and appreciate how hard the staff worked.  All the guests said they had a great time and nothing went horribly wrong.  However there were a couple of negatives:

Guest were placed in rooms all over the hotel complex.  Getting from one room to the next was a headache, the grounds are large, maybe 25+ acres.  It can take 20-30 minutes to walk from one side to the next.  Not fun when your trying to get everyone organized.  If you book (at any large hotel for that matter) insist the guests are relatively close by.   Or preplan where you will be at every point beforehand and tell the guests in advance (although this may not work as you will have to go to the planner to sort things out unexpectedly). 

DJ did not play our music list.  Eventually he did when we asked him.  I think we paid $1,900 so would expect better.

One of the dishes we ordered, beef, was not served, instead chicken.  Not a big deal as the everyone had eaten so much during their stay already.

In summary if you want a destination wedding go for it.  Just be ready incase there are some hicups.  If your doing this to save money think again.  Personally I would have preferred to pick a location were I sourced things but we were living several thousand miles apart so couldn't.  Destination weddings usually mean some people cannot attend but the advantage is you can spend more time than you would at regular wedding with the guests during their stay (great if your inviting people who live far away from you).