Good, so it's not just me. I'm using the AT&T backup connection on my iPad and it's sluggish.
That's what I'm doing as well. Do you pay for that service every month, or just switch it on when you need it (e.g. in cases like this or perhaps when you travel)? Unlimited data or one of the capped plans?
I've been debating whether to keep paying for my service with AT&T. I was one of the lucky ones that got in on unlimited data when it was first offered (they pulled that offer on the iPad pretty early on) and when I've bought successive generations of iPads I've confirmed with them that they would let me keep unlimited data so long as I keep the service active (in exchange for my continuing to buy AT&T models). But now with the Verizon shared data plans, it might be worth it to make my next iPad a Verizon model, especially considering that SIM cards attached to an unlimited data account are fetching a pretty decent price on eBay and such.