I don't notice much lag on my iPhone or iPad 3 when switching to an suspended app. On the iPad mini, there is sometimes a slight lag. However, suspending apps instead of letting them run in the background do save battery. For some people, making sure that their phone's battery lasts all day might be more important than having to wait slightly longer when switching between apps.
Now I'm sure someone will jump in and tell us that this behavior is customizable in Android -- if you want your battery to last all day, then there is a switch in settings somewhere that you flip to stop apps from running in the background. But unless that switch is set to off by default, the regular user like my Mom, or that friend who never even updates any of their apps, won't ever discover it, just think, "oh this phone has short battery life," and just deal with it, or get another phone.
So Apple makes the decision for the user to prioritize battery life over a few seconds wait, and yes, it's Apple's way or the highway, and many power users don't like that. So to them, Android is the better OS. For people like my Mom, I can just hand them an iOS device, and it pretty much just works. I jailbreak my iDevices whenever a jailbreak is avaiable, and tinker to my heart's content, but it's just so much easier to support iOS. Okay, it may not have all the most advanced features that Android has -- in terms of features, I admit, Android has more, does more. But as I keep saying, more isn't always better.
