Read all the reviews before going and was worried to be honest

I am happy to say the reviews are wrong, clean hotel, great staff and food was good.

The hotel which was closed meant a pool which was quiet and we used it due to all the beds being spread out.

I think the best endorsement is that I would go again

We've just got home after a 2week stay here. I'm not exactly sure what to make of it. I will explain in detail shortly but it's true about the break in to rooms as we had the same, food is ok but the drinks are vile, bar staff great but restaurant and management were so rude..... PLEASE READ:
Upon arrival the check in was efficient and staff very friendly, as I got to my room 1043 it stank of damp and urine, I told reception and they said it would be sorted... This took 12 nights to sort after constantly asking. The pillows always stank of urine and they simply swapped them between beds.
The weather was cloudy and raining but the humidity was awful. The 2nd evening we went for dinner in smart vest/tank tops and as we entered the restaurant we were surrounded by staff as though we had robbed the place. We were told that men cannot wear vests but women can??? We asked why as the restaurant is inside and they have NO air conditioning and were told they would send the manager.... This is where it all went wrong! The manager arrived and physically pushed us out of the restaurant shouting in front of other guests saying "IF YOU DON'T LIKE THE RULES, PACK YOUR BAGS AND LEAVE AS YOU ARE NOT WELCOME HERE", a couple witnessed this who's details we now have. We were so embarrassed and humiliated. As a party of 10 we stood out! The next day we spoke to the Thomson rep (Antonio), I've never met such an ignorant, useless waste of space EVER. It turns out he's nothing to do with Thomson and works for HotelBeds so is powerless. We got no help whatsoever from him. We ended up ringing Thomson ourselves in the UK but still got nowhere.
The next evening in the restaurant, staff ignores us and refused to serve us so we ended up walking out due to humiliation! After ten speaking to the other Thonson rep (Belissa!) we actually got somewhere and we're allowed to eat dinner at the Riu Bachetta next door... THAT HOTEL IS AMAZING. We were only allowed to do this for 6 nights and had to suffer the Merengue for the rest of our stay.
Like someone else's comments below, at the weekend the locals are allowed in and there are some dodgy characters around. We also doin items had been taken from some of the rooms and also the safe. We spoke with Thomson who implied we were lying so spoke with reception to the arrogant management and staff... They brushed it off until we demanded the police and told them to fingerprint the room. They came to the room, looke around and said "THIS PROBLEM DOES NOT HAPPEN IN THE DOMINICAN, WE CAN'T HELP YOU" and walked off! Totally unbelievable awful service. For the rest of our stay, the reception staff, restaurant staff and Thomson all refused to speak with us making us feel awful on our holiday... As for the rest, I've broke it down briefly:
ROOMS:
Clean and tidy when not smelling of damp r urine! The air con is ok and does its job. The rooms are very dated but kept clean with fresh towels daily.
FOOD:
Breakfast and lunch was always had at the Bachatta next door and was beautiful. The dinner at the Merengue was hit and miss but could always find something.
DON'T DO THE A LA CARTE as it's simply awful, 5 from our party got sick due to the food.
DRINKS:
Again it's hit as miss, I know u dot have branded drinks when on holiday but the majority of these drinks were awful and not drinkable, as for the wine... DON'T BOTHER!
STAFF:
Bar staff and beach staff were excellent and always there to help you. The guys cleaning the pools are also really friendly... Just be wary of the restaurant staff an management!
ANIMATION TEAM:
Superb and probably one of the best I've known, albeit te shows are not great, they try their best and are super friendly.... Especially Jack Daniels! Brilliant guy!

All in all I would recommend staying at the Bachetta next door which is so much better and safer. You can have lunch and breakfast at either hotel and use the facilities there so just book the Bachata and walk to the Merengue to experience it... U will soon go back to the Bachatta! It's our 1st time to Dominican and certainly the last.... KEEP AWAY FROM THE RIU MERENGUE! Email me if u require any help!

we came back for the third time and were not disappointed!
If you are going to the Merengue don t worry
about a thing! the accommodation is kept spotlessly clean,the food is excellent the beachfront is stunning and the staff are always smiling and helpful-enjoy!

Just returned from a great fortnight at the Riu Merengue.
On arrival our check in was very efficient. Welcome drink greatly appreciated
The rooms are fairly basic but spotlessly clean & comfortable.There where balloons put in the room to decorate it for my 11 year old son (which I thought was a nice touch. Although mini bar only topped up every other day we could phone reception for more drinks at any time. There was also a man on a bike everyevening who was happy to give you extra.
The food was varied & there was something there for everyone every time (Two of our party are quite fussy eaters). We booked the steak restaurant on the night of our friends birthday & they supplied balloons & cake free of charge. Look out for Lidia the waitress in the main restaurant although every one was very helpful & efficient we felt that she went that extra mile & provided us with terrific service.
The bar staff couldn't have possibly worked any harder than they did. Even when the bar was busy we didn't wait long for a drink. During the day they would come around the pool & even on the beach to take orders for drinks.
The maintenance team seemed to work constantly cleaning the grounds pool & buildings.
The entertainment team worked really hard & made the holiday fun. We especially loved Jack Daniels, Tequilla. although we could not fault any of the others. The evening Entertainment was ok. A few dancing show's. Michael Jackson one very good & Africa show great. Magic show good although I don't like the fact they used birds & animals in it,& the comedy show performed by the entertainment staff gave us a good giggle. There is a kids club that looked like they provided fun for the little ones. As a party of four adults & an 11 year old we did not find the pool to be too noisy.
I have read reviews saying that the Dominicans come & take over the hotel & the weekends. I do not agree with this at all. We did not find them any louder than other families & after all it is the Dominican Republic so why should't they go to a hotel nearby.
Our Thompson rep's provided a really good frecyling service. People left their suncream insect repellent etc, so if you run out ask the rep
Overall excellent holiday