I picked up a copy before I went to Reno for the first time, and it was tremendously valuable. Any time you're going to a venue (or thinking about going to a venue), it's a very convenient source to get basic information on the games available.
Now, if you're looking for info on places that you visit regularly, then, well, it's not really so necessary, since you visit them regularly.
Some of the info, like penetration, number of tables open, and minimums, can be tremendously variable, so all of that needs to be taken with a giant grain of salt.