Before going to Japan I spent about a month learning how to read both Hiragana and Katakana.
In general, I found that knowing Katakana was IMMENSELY helpful to me. I was blown away by how much of the everyday Japanese language is composed of English words written out in Katakana.
It was especially helpful while eating out. Not every restaurant in Japan has a picture or English menu available, and more than once, I found myself needing to read both hiragana and katakana to figure out what to order.
The bonus with katakana is that when I could read something like "Ma-n-go-sa-u-a-a" on the drink menu, I learned to recognize that as a "Mango Sour." At cafe's (many of which DO NOT have english menus) I had no problem distinguishing the Latte from the Hot Coffee.
Obviously none of this is required, but it definately made the trip more fun for me to be able to read some of the language. Now I am learning Kanji for my next trip!
