2) Single code runs in all platforms (iOS, Android, Windows 7, mobile web) which makes our lives easy and saves lot of man-hours.
3) You can easily create build files(.app/.apk) for testing in itouch or iphone or in droid phones.
4) You can still take advantage of distribution and integrated payment via the App Store or Android Market
1) Poor performance while interacting with device parameters like camera, folders etc. For developing games its also a pain in hybrid platform. You can implement caching or leverage some 3rd party solutions (i.e. Sibblingz) for native graphics acceleration but for the most part a native app is much faster/smoother than hybrid web app
2) UI is always been a problem with hybrid app. You will miss lot of prebuilt effects for touch/scroll. While working with native app you can bring those effects easily. Now a days, jquerymobile brought some fresh air though for adopting effects in hybrid environment.