He is a good player...a near perfect one for Barca. I took some time to observe him after Xavi was hallucinating about him some years back. I did watch a lot of La real matches because of him, trying to see what the noise was really about.
If you want your pivot to be the one that orchestrates your attack, with short 1-2 passes and build organically from the back,in a controlled tempo, he is shoulders above any other DM that has been mentioned for Barca. He plays similarly to a resurgent xavi of late 2000s and early 2010s. A little glimpse of his style is what you saw as soon as he came on in the Euro final and his contribution to the winning goal. If you want to control matches, impose your style and build your attack from a pivot, Zubimendi is the one, but if you prefer a one pass and move, combative and physically dominating DM for your style, look somewhere else.