<p>Hard.</p>
<p>You need (in this order) good research experience, strong letters of rec., and top grades (from what I’ve heard, a 3.8+ will serve you well) and GRE scores.</p>
<p>Being out-of-state doesn’t matter in the admissions process, but you have to pay extra tuition (which adds up to about $10-11K/year IIRC).</p>