Yes, that's good stuff. It's quite pricey if you are feeding lots of tortoises, but for one tortoise, its pretty good. I use it occasionally for my baby tortoises.
Been waiting for something like this to be available in the uk as we can't get mazuri over here, I'm very pleased with it, my leopard is happily munching on this, mixed with his usual diet. (2/3 times a week)
Mine had no interest in it at first either. I soaked small amounts and mixed it in with the greens at first. It took a good couple of weeks before they would readily eat it.
I have not tried all the commercial food directly with the tortoises I have. Some in the UK I've not seen here in the US, like the Komodo foods.
But of the diets I have tried, both by label/content inspection and on a food plate for the tortoises. It seems to me that the ZooMed grassland and forest species diets are the only ones that hit both criteria, good ingredients and acceptable to the tortoises.
It's not the equivalent of ice cream for children at all, so as Tom point out it takes some persistence. But once they start to eat it, the internal tortoise feedback "what did I eat" loop signals them to eat it again. Like Yvonne says it is not inexpensive, and I certainly would not want to maintain several hundred pounds of sulcata tortoises on it. But for the smaller species with a few individuals that cost difference is marginal.