The battery life is rated at something like 50% brightness, so of course it will not match those at 100%.
And did your battery start at 100%? If it started at 90% and you lost 40% in 3 hours (perhaps a bit more, assuming there was no stopwatch involved) while at 100% brightness most of the time... seems about right.
I'm wondering how you could possibly ask this question after running your screen on full brightness for a couple of hours....
Why don't you try using your iPad in conditions somewhat remotely similar to what Apple did in their testing so you can at least get a more realistic picture of your battery's performance before you post saying your battery is going "quick"?
"Testing conducted by Apple in February 2012 using preproduction iPad units and software. Testing consisted of full battery discharge while performing each of the following tasks: video playback, audio playback, and Internet browsing using Wi-Fi or cellular data network. Video content was a repeated 2-hour 23-minute movie purchased from the iTunes Store. Audio content was a playlist of 358 unique songs, consisting of a combination of songs imported from CDs using iTunes (128-Kbps AAC encoding) and songs purchased from the iTunes Store (256-Kbps AAC encoding). Internet over Wi-Fi and cellular data network tests were conducted using dedicated web and mail servers, browsing snapshot versions of 20 popular web pages, and receiving mail once an hour. All settings were default except: Wi-Fi was associated with a network (except for Internet browsing over cellular data network); the Wi-Fi feature Ask to Join Networks and Auto-Brightness were turned off. Battery life depends on device settings, usage, and many other factors. Battery tests are conducted using specific iPad units; actual results may vary."
Don't mean to be a killjoy but my battery is doin good. Almost 10 hours strong on a 86% charge. I'm down to 22%. Cellular turned off, 50% brightness. Been downloading apps, games included and browsing the web on wifi.