Mansion is a really great map that features a large inside area and large outside area with multiple locations to enter the mansion.
Teams will often stay camped at the top of the mansion area overlooking the doorways, which can be a good tactic except that unless you are all paying close attention an enemy can easily and quickly end up behind you all as there are so many entrances and doorways to keep note of.
Sniper rifle is situated at the top of the mansion stairway in the middle of the map. Boomshot is outside with grenades overlooking this area. A quick throw of the grenades in a drawn out battle for boomshot can quickly unlock it for your team if done quickly. You can take boomshot and suprise the sniper camping team with this weapon if you use it with precision.
Overall this map offers a lot of opportunties to flank, mixed with a good amount of competition for each power weapon.