The only way to know if something is "worth" the number of credits is to figure out how much a "credit" is worth.
My math is like this:
1 snack ($4), 1 CS (figure around $13) and 1 TS costs $40. So 1 TS is $23, 2 are worth $46. Now look at Jiko's menu. Will you order the equivalent of $46 or more there? If so, it's "worth" 2 credits.
Now let me just tell you that we love Jiko. Because of Jiko, we're actually staying at AKL this week. It's one of 2 restaurants that my d requested (HBD was the other). But we don't do the dining plan, because I hate doing these calculations! Jiko to me is "worth" what I pay for it, without worrying if it equals the amount of a credit.