In competitive commercial environments it is refreshing to be surrounded by motivated and determined colleagues, ultimately striving to progress themselves and their careers.
In theory a colleague finally getting that long-awaited promotion to management is a positive. The individual feels motivated and rewarded, whilst the team see's the reward of hard work and what is possible if they apply themselves in the same way.
However, the situation can be awkward for both the team and the manager. The transition from peer to leader throws up an interesting dynamic, with lots of new managers opting to be too firm, in an effort to stamp authority. Or alternatively being too lenient, typically a result of fear of losing their peer status.
In my experience the key to ensuring the right balance is found by new managers, is to provide continuous support and leadership development. All too often new managers are promoted and left to their own devices, the best future leaders will value further development and encourage guidance over situations like the transition from peer to leader.
As a leader, your role isn't necessarily to be liked, but to be respected and have good rapport with your team. New managers often transition from a peer to a boss, and they can become overbearing or too permissive.