All seems quite premeditated, to be out and about carrying a knife etc?

Well, observations :

1. If the lady / dude spoke to the 2 guards, presumably to ask about the whereabouts of the ladies room, neither of them picked out the hint of a man's voice trying to sound like a woman's? Chances are it was a woman not a man.

2. The time-line of the video (if it is correct) states she went in at 13.13 pm and came out with the running crowd at 14.45 pm, thats about 1 hour and 32 minutes of waiting time inside the washroom. Had there been an argument, which I presume should entail loud voices raised, thats a might long time to be arguing without the authorities being called. So maybe she was waiting there for either :
a. any foreigner to show up
b. or a particular person to show up who happened to be a foreigner
and either way it was an ambush and done very quickly as obvious by the running crowd and the trail of blood.
3. The fact that the person wore completely covering clothes show that the person obviously knew about the presence of cameras and the calm walk out of the lower lobby shows that there were accomplices waiting maybe?

I think this was definitely per-planned and most probably acted out by a woman with partners helping. Political or personal, now that the authorities will figure out soon enough.

Either way it is shocking to say the least and my condolences to the victim's family.

If it was premeditated against a certain person, how would the killer know that the victim would go to the toilet?

How would they know that the victim had arrived? Did the killer check out every person entering the toilets?

Why did the killer need to ask where the toilets were if pre planned?

I am reading the comments in the Daily Mail about this story and came across the below:
Ok so just how competent are Dubai police?

Woman in burqa in Abu Dhabi lay in wait for woman before stabbing her | Daily Mail Online

I agree it is very awkward. Specially about talking to the security guy..

The only thing I can think about (pure speculation) is that that food court would be popular with foreign teachers, i.e. going for a coffee or lunch every day at that time. It is not uncommon that expats gather in the same places and have pretty fixed routines.

So maybe the person in niqab was just waiting for one of them... hence the 1h 30' wait inside the toilet. So maybe "it" was not waiting for a particular person but for a particular profile, by reading this October warning:

Messages to U.S. Citizens 2014 | Embassy of the United States Abu Dhabi, UAE

That's why 'she' picked up the Abu Dhabi Weekly on the way in!!

More observations:
1. I refuse to believe that there are no outside cameras noting the car that picked her up.
2. The fact that this act was done on one of their national days can't be lost on anyone as a message being sent by someone to the UAE authorities to 'cease and decist' in whatever they are doing?

maybe she got a text message telling her to come to the restroom...

There are cameras at exits of parking at Boutik. Not to say that they were working.... The killer could have changed out of outfit and calmly walked back up to mall or disappeared in a car. I was at mall a few hours later and there was no police presence at all. The mall and Reem island should have been in lock down mode.

It was the day before National Day, doubt it was linked to that

I heard that this was done as a smokescreen to avoid the national-day pan-pipes

the ID parade...

The one on the right.

You're just saying that because she's black

Decent shirt potatoes though.

The Sand Pit seems to be getting back to normal. A thread about a very serious event but with a scaremongering title elevated itself (a bit) with some reasoned views only to plummet by page 2 into comments on the size of a cartoon character's boobs.