Here is what the support document at Apple has to say.
A very small number of iPad users have experienced issues with Wi-Fi connectivity. This article outlines workarounds for these issues. Apple will also address remaining Wi-Fi connectivity issues with a future iPad software update.
This isn’t the first time Apple has acknowledged the issue. First Apple confirmed the iPad Wi-Fi issues almost 4 days after the US launch of the device and these Wi-Fi issues have exactly been the reason why the iPad imports had earlier been banned in the Israel.
These iPad Wi-Fi issues have also been experienced by users in wide hot-spot areas such as university campuses. The Princeton University case being the most noticeable one where the IT authorities of the university had forbid the use of the iPad in the campus due to it not being able to renew it’s IP due to an issue in the OS.
As of now Apple offers some resolutions such as updating the Wi-Fi router firmware, adjusting the screen brightness and renewing the IP address manually.