It is only occasionally noticeably faster, and the rendering is far worse. Mobile Safari is great because it actually renders sites appropriately. Opera mini is great because it's faster than your built-in phone browser, but it doesn't compete with real browsers even when it's marginally faster.

Also, the speed benefits are significant, only if you are on a slow connection.

Probably wary of bad publicity (for once) Apple accepted the application… and since then Opera barely touched it. No update to the non-standard look&feel, no update to the non-standard settings management (and widgets), no update to the awful zoom… and apparently barely useable on the iPhone 4…

And since they have't done any update to it since May while they released 5.1 for just about every other smartphone, I'm not exactly expecting anything.

What they say about the economics of mobile bandwidth and computing power vs. server bandwidth/CPU rings true, however. The trick would be to optimize the rendering for specific mobile browsers. One could even use the "native" rendering engine to do this. Apple should implement this trick for mobile Safari, optimized for the specific screen sizes of the various iDevices. Not only would this save rendering time and battery power on those devices, it would enable yet another advertising strategy for them.