1. Why are you so late ?
Engadget Question :
It's been nine months -- nine months! -- since Acer first announced it was getting into the tablet game, with a promise of both 7- and 10-inch slates. Well, the 10-inch Iconia Tab A500 has been on the scene for months, but until now we've been tapping our feet impatiently waiting for the other tab to drop.
the answer is the Honeycomb & : 600x1024 , A100 is late, but it is the first 7" Honeycomb tablet !!
2. The bargain factor
the 8GB version costs $329.99 while the 16GB number rings in at a reasonable $349.99, undercutting the 16GB HTC Flyer by $150.
The big draw in that case will almost certainly be the price: the 16GB A100 costs $150 less than an iPad or Galaxy Tab 10.1 with the same amount of storage. It doesn't hurt that the A100 is fast and runs the latest version of Android (granted, that's a feature mainstream users might not care about).
3. Other 7"
As for 7-inch tablets, your main options aside from the A100 are the original Galaxy Tab, the BlackBerry PlayBook and the HTC Flyer
other view from Android Community : Acer Iconia Tab A100 Review