I can sum up why the iPad is better in one word: battery.
The top end Android tabs give it a run for its money (Xoom) but most are just pointless devices with their pathetic 1-3.5 hours battery life. From what I've read when Apple claims you will get 7 hours, you will actually get that period out in the field.
Plus, I own an Android phone, the OS is good but not nearly as polished as iOS and it also lacks a good app' store (Android Marketplace isn't "good"). So I cannot see myself paying the same price for an Android devices as I would for iOS - my phone for example cost 1/5th of an iPhone.
I think it is the right decision to buy an iPad right now. The competition isn't either cheap or good enough to be "good value" (value = price/quality).
I've got a samsung galaxy S phone running froyo and I find it just as "polished" as the IOs4.
I get a full day of use on a single charge (assuming limited web surfing, music streaming).
And I really don't find the android market to be lacking.
I will grant you there are some small issues with sensors from time to time, but they will be worked out soon enough.
Being locked into itunes alone is reason enough for me to avoid anything apple.