I think they did it this way so that developers wouldn't have to code yet another resolution for their applications. Unless they find a way to shrink 2048x1536 pixels to a 7.87"x5.3" screen. Images are still sharper on the iPad mini than they are on the iPad 2 since they shrunk 1024x768 to a smaller screen. No it's not retina but that may not be an option, technology wise, yet.
The one thing that I can't stand about Mission Control is that it's a four finger swipe UP to activate vs in Snow Leopard, Exposť is a four finger swipe DOWN to activate. Other than that though, I like it. I haven't seen a difference in Spotlight, though (probably because I only used it to launch apps, and I use Launchpad to do that now ). Though I like how you can Quick Look via Spotlight, now.
I usually use QuickSilver, but I prefer Spotlight from Tiger to all other versions, to be honest XD And then there's the loss of Rosetta... I don't want to be rebooting every time I want to use a PPC application. Also, I'm not a fan of the iOS-like features in Lion
I never really used Hot Corners. The only one I used was the one that puts your Mac to sleep.
I never really got into QuickSilver. I also never really used Tiger. I got my first Mac when 10.5.7 was the current version. The only Power PC app I use is Photoshop CS2 and I don't use that every day so restarting isn't a hassle. Plus, I don't have to worry about quitting anything when I restart because of the resume feature.