Hi sajnanik and welcome to the forum!!
I went up to Las Arenas last night, not expecting to see anything really. That was until I saw underneath Toys R Us, there were Las Arenas signs up like they do when a new store is opening and a silver shutter down in the doorway with a simple A4 piece of paper saying those magic words "Primark".
There is a little café by the escalators and people must have thought I was a right loon taking pics of a shop that hasn't even opened.
Judging by the second photo we may still have to wait a while as it is pretty much a shell. Couldn't get much more into the photo without losing my iPhone through the shutters lol. I'm also surprised that Primark has come to the islands but with it's slashed prices there will be a lot of happy people, including myself.
I checked out your blog, it's pretty interesting!!