Good agenda/calendar app -- but the free version is really too stripped down to be of much use. (This really is a "trial" only.)
It had good functionality (better than the iPhones own calendar) -- but lacking in look and design (not your typical slick iPhone app aesthetics). Also, its annoying to see the effects of poor translation (from Japanese I assume): weird labels, plus spelling and gramatical errors in the instructions. Would really benefit from the suggested emhancements in all of the other reviews too.
If you need a more robust calendar/agenda than the iPhone standard, the $10 version is probably a good bet.
If you simply want to synch "over air" to your Google Calendar (and to your GMail contacts), its better to simply synch the iPhones own calendar directly instead of using a third party app. (Instructions to set this up are on Google -- and it works well. Just be sure to power off/on your iPhone after setting up the synch). Youre limited to the iPhone calendar functionality, but the Google Calwndar synching is easy and seamless.
Norbert1234 about SaiSuke Lite