I recently stayed at the MGM Park and had a pleasant experience. The staff was very friendly and courteous. I found the cocktail service on the casino floor to especially good. I only drank bottled water but found the waitresses to be efficient coming by often. I mention this mainly because I often see the drink service (or lack of drink service) to be a criteria people use to evaluate the casino. I thought the casino itself had a good selection of slots. I didn't play any tables so I can't comment on those.
I didn't experience any major problems during my stay. The room, a double queen, was clean and nicely furnished. The carpeting in the room looked rather worn and the color didn't complement the room color. I don't know if this is something that is going to be done later or if they just elected to not replace the room carpeting. (Or perhaps my room had just gotten worn. The rooms are not the same you're going to get at the Wynn, Cosmopolitan or Delano, but for an inexpensive stay they're certainly adequate.
The biggest disappointment was the lack of restaurants in the complex. There weren't any 24 hour places (or if there were, I didn't find them). I was thinking of eating one evening about 9:30 pm. I only found Primrose open and their menu didn't appeal to me. Fortunately, there are a number of restaurants close by. I did eat at Primrose one morning for breakfast. The outdoor dining was nice but the food was very bland.
Others have mentioned the construction noise. I too heard it but was on the 22nd floor and it didn't really bother me. If I had been on a higher floor, I don't know if I'd be complaining or not.
One final thing I'd mention is the check-in kiosks. I'm accustomed to asking for a general room location. (i. e. facing the mountains or perhaps a room on the upper floors). The kiosk didn't give me that option and I didn't ask the attendant who assisted me if that was an available option. I didn't know where my room was until it gave me my assignment. So if room location or direction is important to you, you should ask the attendant if adjustments can be made.
I don't think this will ever be on par of a high-end hotel. But once construction is completed it's convenient location to the south end Strip and presuming continued reasonably priced rooms, should make this an even better place to stay.