I went to Iber Barca 2018 and Cascais 2019. I recommend it and the Referee Abroad org 100%. I had a brilliant time at both.
It might not be for everyone though... some things to consider:
The Barca edition is at a complex outside Lloret de Mar.
Lloret is a teenage party town.
The pitches are a bit small so the more competitive older games can be explosive.
The complex itself was not glamorous when I was there but the town is great fun.
The conditions are challenging (heat!) and the football was challenging enough for me at the time! Though by Iber/Ref Abroad standards this is entry level.
I would very much recommend if you are ready to meet other refs, drink a lot of water, probably fits if you have been reffing for at least 2-4 years and are under 25. If you are older then you should be prepared that Lloret is a teenage party town. For a first foreign tournament it is a great shout as it is a little more relaxed than others - also as it's at one complex you don't have to be distracted by independent travel.
As said, I can't recommend enough. I went to Iber Barca at 44, met some wonderful people, made some lifelong friends, had the game of my life, and definitely improved as a referee and probably as a person!