You don't have to worry about billable hours, and job stability can be higher. However, it can also have its challenges.
1. Although some in-house lawyers manage to work sane hours, an all-hands-on-deck crisis can easily lead to you pulling an all-nighter.
2. The compensation for in-house legal teams is often lower than what you can make in private practice - although it is more stable over time. It is also a salary, meaning that when you do have to pull an all-nighter you get no extra compensation.
3. Your boss, because he's paying you anyway, may reach out to you for things which appear minor or stupid, or which aren't even technically legal matters at all.
4. If you are the sole counsel, then you may be in a very lonely place. You will have to find support outside the company, such as through networking or professional associations.
5. You will have to be more of a generalist and may have to step out of your comfort zone and research areas of the law in which you have less familiarity.
6. In private practice, you have more control over who you can hire and fire on your team. When working in-house, HR has a say - and you will be working with people that you may not get on with and dealing with more complicated office politics.
7. You have to make more decisions and be more aware of the larger picture and exactly how the company you are working for operates - meaning that while you may not be worrying about finances in the way you are in private practice, you do have to worry about how what you do affects the health of the company as a whole.
8. You will need the right practice management software - one which is designed to support in-house lawyers rather than practices, which can be a challenge, especially when you have to get it past IT.
Working in-house can be a great way to have a stable, long-term career. It can lead to working fewer hours than in a practice and some find it less stressful. If you are an in-house legal counsel or looking for work, then contact LawMaster to find out how their matter management software can help you.
Sources:
http://careers.findlaw.com/how-to-find-a-legal-job/private-practice-or-inhouse-choosing-the-right-path-for-you.html
https://abovethelaw.com/2014/07/is-it-more-stressful-to-work-in-house-than-at-a-law-firm/
http://www.legal500.com/assets/pages/gc/winter-2014/what-i-wish-id-known.html