Pros
I fled a large university press to work at SAGE, and have been grateful for my decision and for SAGE ever since. I've never worked for an employer that valued its employees or its mission more (and I've worked for the largest non-profit "mission-based" publishers in the world). The benefits are stellar, the colleagues are wonderful. You hear the word "culture" a lot at SAGE, and you hear a lot from SAGE about how the company shapes and fosters its own culture. In fact, "culture" is so ubiquitous that it induces a fair amount of eye-rolling among middle managers and long-time employees. Well, they have the luxury of cynicism, because most of them have been at SAGE for over 10 years. I still haven't forgotten what it's like to work elsewhere, and for me, SAGE culture is a breath of fresh air. I'm proud to work for a company that actively emphasizes the value of the employee and how our contributions make the world better. Also, we have 1) an engaged and active HR department who 2) aren't temps and 3) actively ENCOURAGE public feedback on Glassdoor so that they can continuously improve.
Cons
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.