We just returned yesterday (Dec 3rd) from our second one week stay at the Gran Bahia Principe Akumal. We stayed the same time last year and had a similar enjoyable experience (which makes for a nice consistent expectation when you only have a week a year).
We did change it up a little this year by booking in the Royal Golden section. It was only a few dollars more and we got an extra a'la carte and a great room that overlooked the beach. The other so called "perks" were not really evident to us, but we'd book in the Royal Golden again just for the aforementioned.
As most others note in their reviews, the complex is big and kept immaculate. A small army of friendly staff are constantly cleaning, entertaining and serving your needs.
As most are probably more interested in the negative aspects of a vacation resort, I'll touch on those, but keep in mind the positives by far outway them:
1) Rooms are a bit dated, ordinary and are starting to show their usage. The sound proofing between the units is not very good and you can especially hear your neighboring conversations when in the bathrooms (through the venting). Beds are very firm and only have an add-on foam topper. They are kept very clean by the housekeeping staff.
2) Room safes require the daily rental of a lock and key ($5 per day). Not a big deal, but most other resorts where we have stayed have combo/code locks that are free. Not a big deal aside from having to carry a key with you or hide it in your room.
3) Food is just okay in the buffets with little quality selection as far as beef and seafood. Chicken dishes are always dependable and pork is a bit hit and miss. Side dishes are plentiful and deserts are not that great. In the a'la cartes food is better (as you would expect), but the steaks and such lack the quality of true 1st class dinner that you may expect back home. Still good value, just don't over expect.
All in all the resort is great value for what it is. The things mentioned above can be resolved at some other resorts (we've stayed there too), but you can expect to pay a lot more. With that in mind we'll likely go back to the Bahia... maybe for two weeks next time?!