Pros
I've been developing iOS apps for them for the better part of a year now. What I like about them is that they value your skills and input, and treat you like an expert (after all, that's what they hired you for!). There's a lot of autonomy for you to do what you are best at, and they treat you more like a competent partner that's a part of their family rather than an employee that needs to be micromanaged and told how to do every little thing, which is highly appreciated.
They also have all the typical perks companies offer and then some, which is always welcome. Unlimited vacations, great healthcare options, and so on.
Work-life balance is encouraged, they value having their employees be happy. I have not met a single employee suffering from burn out. Your best work is encouraged, but it isn't to a point where it becomes burdensome.
Employees and culture are excellent, everyone is respectful to each other and helpful.
Cons
Only difficulty with Coplex is when you first start, it takes a few weeks to assimilate to their culture. You have a lot of autonomy and it will take some time to get into the swing of things. Honestly, I can say this about most places when you first start. Coplex does give employees a little less guidance and more freedom, and expects employees to be responsible for their own workload, so this might be a little more true here than other places.
Having said that, the struggle only lasts at the beginning. Once you overcome that hump, it's one of the most fulfilling jobs you can have.