Pros
Large organization with apple opportunity to develop a career supporting conservation. Mentorship programs exist and cross training opportunities exist, but you must seek them out yourself.
Cons
Work experience is highly dependent on the quality of your manager. Managerial training is minimal and management of direct reports is often treated as a "perk" for long time service with TNC rather than a need of the organization or the skills of the individual managing staff. This results in many middle management positions that are not needed and managers who are not prepared for or suited to their responsibilities to lead teams. Most are performers of a given expertise (like sales or operations) and as such are still expected to perform such tasks while managing a team. This can often result in managerial responsibilities and staff development coming second to completing more familiar, defined projects with deadlines.