The entrance is for ALL
Disneyland Resort hotel guests.
We stayed in the Dreams Tower, and instead of walking all the way through DTD, to the esplanade, into DCA, and up to Grizzly to get to TSMM, we opted to enter GCH through the DTD entrance (between Club 365 and Sephora), then use the DCA entrance, which puts you right near Grizzly.
We never checked out the distance of both ways, but hubby felt it was shorter to go through DCA, and it certainly was less hot.
Now, if your plan is to go on Soarin', or if you're going later when the rest of the park is open and you want to go on TOT, I don't think it's a good plan at all...since we wanted proximity to Grizzly and we were heading to TSMM, and the way gave us a head start on getting that way, it worked for us, but having to backtrack wouldn'tl have made me happy.