Ipad's wifi is defintely not optimal. I have 25mbps dsl at home and the most the ipad will show is 10mb down. My Asus netbook can get 24+mbps downloads all the time.
Uploads are the same on all of my devices, about 1.7mb
I wonder what the bottleneck is?
This was documented a while ago.
It was the hardware design of the iPad1 and the antenna's inside that made it physically incapable of using Wireless N speeds.
The iPad was Compatible with Wireless N but it was not really a N class device speed wise.
The following is probably not 100% accurate, but from what I read it's because N needs multiple Antenna's to get it's speed. The iPad only had 2, which was it's limitation. Proper N devices like Macbooks had 3 or 4 which meant they were able to take full advantage of the N speed.
We have no idea yet if Apple have improved/fixed this with the iPad2.
Many many people, like you have commented the same that the iPad would not get the same data transfer speed at their other home devices, and this, as I've described above was the reason.
Perhaps it was a batter power issue, or perhaps it was a chip speed limitation issue which made Apple not fit proper N class speed to the 1st iPad.
Until people actually get them in their hands and do tests against the original models we just don't know if they have fixed this.
Apple may just feel it's good enough and does not need to be any faster in this respect.