My complaint about Gallery 3 is that they lost the "individual registrations" that Gallery 2 had. I run an interest-centric web site and members had been able to register and post their own pictures. With Gallery 3 they have no way to register now.
I also found the menus confusing to most people. But that issue may not apply here if the OP will be doing all the posting himself.
I, too, will be interested in hearing what other suggestions there might be.