One of the things you are paying for when buying an iPad is a higher quality touch experience with faster response times. Agawi has published their touchscreen latency analysis findings and the iPad Mini has landed on top.
The test was performed using a system called Touchscope and all tablets are prepared using the same software and methodology. The results (shown above) put the iPad Mini ahead of the pack but not wildly ahead of the 2nd through 4th places. The speeds are measured in milliseconds and the results are based on a minimum of 50 tests.
The question you are likely asking is about how much difference the various speeds make when using a tablet. I found a video that demonstrates the differences and I was surprised how much even 50 ms can make.
While the Galaxy Tab is almost unusable, the Surface and Kindle Fire are both relatively similar to the iPad. Even the iPad has room for improvement and it is likely that it will continue to improve. The iPad 5 recently tested at 72 ms which is just under the iPad Mini, but it will be interesting to see if there is any improvement with the new iPhone 5s.
These tests are performed under optimal circumstances but that isn’t how most of us use these these devices. I bought a Kindle Fire for my kids a while ago and they hated playing Angry Birds on it because it was harder to play than on the iPad and when I tested it out I noticed the touch experience was much different than on our iPad. It’s hard to say which other apps were running or how much memory was tied up with other tasks.
As a musician who uses the iPad to perform and as a mixing tool, having the fastest response time possible is a big deal. Latency isn’t an issue when I play a note on my real piano but it is when I play a virtual piano on my iPad. I expect the response speed to continue to improve with each generation of iPad until we eventual reach sub-millisecond speeds.