In the most general form of "across the street," yes, it's across the street. It's in the far SE corner of California Adventure, at Harbor and Katella. That means it's about a 10-12 minute walk. You'll effectively be walking from the back to the front of DCA, but on the outside of the green fence, then using the pedestrian walkway to get into the esplanade.
It's been getting okay reviews, better since their remodel, I believe. I've never stayed there personally. How good is the rate? We might be able to find you a better rate at a closer hotel.