Entry-level publishing jobs are very hard on assistants, whether they're in production, editorial, or marketing, and the work is really uneven. Some assistants have more free time than they want; others have an utterly crippling workload. It seems to depend (too much) on who they're supporting.
I get that assistant salaries are generally low because they need a lot of training and mentoring, and to be fair, SAGE is great at promoting from within. But assistants and non-exempt employees should probably be afforded more perks than their managers - thinking here of professional development, day retreats, or summer Fridays. Because assistants can and often do feel very burnt out.
Also, SAGE's publications are pretty limited. No trade books, no academic monographs, and few professional books mean that the lists are fairly boring and a lot of your output is inaccessible to lay readers. It doesn't just mean that your job is a little less cool than other people in publishing; it means that you will have fewer transferable skills because you "only" work for a textbook/journal publisher.
Finally, all the benefits are great, except for the 401k. You don't get any company contributions until you're vested, which takes two years. Company contributions only START after two years (i.e. there's not a growing balance held in escrow until you're vested). And the contributed amount depends on company profitability, so you can't really plan around it. This all makes it kind of painful to save your traditional 10% toward retirement.