I've had a few Easters and always kept the shop open as normal, no issues. I think it's a really hard holiday not to be aware of and account for (from the buyer's perspective), even if you don't celebrate it, because Good Friday means even more things are closed than over Christmas.

I've never had any problems with buyers (no where is my item questions, or even low DSRs), but I do alter the message I send just to include a quick note about when the item will be posted and so forth. Especially if they buy say on Thursday afternoon, since it won't get posted until Tuesday, far better to give them some info ASAP than to rely on the auto-update emails, which won't happen until 4-5 days later.