Yes, Google Reader is a convenient application better than using the web page.
How to setup the update frequency? I am using Rss websites links so a daily update is enough. It seems much more frequent and i am worried on battery life impact. I couldn't find any options in Google reader or settings options to change the frequency.
Well there's no such option in the app to control the update frequency. But there's an app in the market that could help you..
Follow these steps:
-Go to the market and download "Synker beta - The Sync Widget" android app
[Read review of the app at the following link http://goo.gl/O6099
-Now go to the homescreen and add the app's widget "Synker"
-After adding settings screen will appear and all your synced accounts will be shown there. By default all are selected. So you'd need to de-select all other accounts except the "Google Reader"
-And under the Widget Label field give any name like "Sync gReader"
Now every time you want to sync Google Reader.. just tap on the widget
To switch off auto sync for google reader go to settings>Accounts and Sync>Select Account> de-select "Sync Google Reader"
Hope it helps