Before you can decide whether or not you will shell out some cash for a Zagg cover, you should first focus on getting off the fence - trying to decide whether a screen protector is a good investment - and should become aware of the fact that a screen protector is an absolute necessity; unlike a computer, where you simply look at the screen (and try to avoid touching it at all!), the iPad requires you to touch the screen all the time, and because the screen is your connection to your iPad, protecting this connection will be absolutely vital.
Now that you have acknowledged that you do, in fact, need a screen protector for your iPad, you should realize a few things about the Zagg cover: although it certainly works well, in its charge of protecting the screen of your iPad, it also has a tendency to get bubbles when you put it on - and there is really no way for you to adjust it (without ruining it!) once you have applied it to your iPad.
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On the other hand, you may want to look into the iVisor; for about the same price as a Zagg cover, the iVisor will block glare on your screen, will protect your screen, and is guaranteed to not have any bubbles at all. What's more, you can remove and wash the iVisor - so if you are trying to decide whether or not you should buy a Zagg cover, the answer may in fact be no, but an addendum to this answer would be this: You should definitely purchase a screen protector for your iPad, and you really cannot do any better than the iVisor cover!