Now before you jump down my throat you should know that I'm a Van Cleef fan. I bought the original "Sabata" and "Return of Sabata" because LVC was in it. I bought this one to complete the set, even though I expected to hate Yul Brynner's intrusion into LVC territory!
Well, the plain truth as I see it is that, in terms of production quality, IMHO this is the best of the three. It was a fun romp with good use made of the Almeria scenery and some lovely touches of direction (for example the thrown dagger through the portait, which then cuts the portait in two as it follows the unseen victim falling behind it. I also detected subtle homages to other spaghetti westerns, for example the closing music cutting in just as the 2nd lead was about to scream a parting curse at the lead - a la the ending of "The Good, The Bad and The Ugly".
Speaking of which, the music was quite good, recalling the original Sabata theme in fresh ways (music by Bruno Nicolai).
Yul Brynner wasn't bad in the part, though his shirt open to the navel irritated me a tad: he just needed a big gold medallion to scream "70s!".
So, while I'm sure that LVC would have been just as good in this role, in all honesty I can't discount the movie just because he was absent.