It is an exciting form of the game which allows for the ball to be kept in hand and with the greater space it allows for players to display their individual talent. Whether it's using good footwork to beat a defender or a combination of footwork and distribution skills to create space for a team-mate.
Sevens places a great stress on a number of key attributes. Players are faced with many one-on-one tackles so they have to be sound defensively. They must be able to distribute the ball accurately through wide passing and in contact.
It is essential that the player has good footwork and acceleration. On top of that, it is essential that the player has good spatial awareness and therefore the ability to identify where the opportunity is to attack and exploit this.
The structure of the Sevens game means that it allows for games to be much more fluid and less pattern-orientated than 15-a-side rugby. This is generally because there is a little more time and space as teams cannot press so vigorously in defence and due to the amount of field they have to cover. Also in the knowledge that a mistake almost inevitably leads to a score, teams tend to be a little more cautious.
I think too with the short halves the pressure is on to score quickly as the games turn very quickly, an opponent can gain the upper hand within a few minutes. This, I feel, encourages players to take more risks, where as in 15-a-side you can take a more measured tactical approach.
The obvious challenge is getting yourself orientated to the space on the pitch and this puts pressure on you defensively and offensively. From a defensive perspective, it means you do have to be more patient in defence and ensure you do not get drawn into making a decision which leaves too much space to cover in a one-on-one tackle or an easy overlap for the opposition to attack.
Offensively, the Sevens game places pressure on every player's distribution, ability in contact and their decision making skills. The ball is precious as the game changes so quickly and therefore every player must feel confident in every facet of their game.
I think the Sevens game has become more physical and the skills you gain through your defensive work in 15s are essential in the Sevens game, particularly being able to slow the other team down when they are attacking to allow your defence to reorganise. The other aspect is the continuity work you do for 15s is essential, as you have to be able to offload in contact effectively.
Although there is some organisation, you spend less time on organising patterns and set piece plays. Obviously training has to be geared more to successfully completing decision making drills under pressure and accuracy of players distribution.
Also, each session involves a substantial fitness hit due to a higher concentration on playing controlled games to improve the players' ability to make the right decisions defensively and offensively in a match environment.
I think you can hone your decision making skills, footwork and distribution skills in the Sevens environment. This, allied to improvements in spatial awareness, allows you to be more effective when in a one-on-one, trying to create space for another player, making the right decision when you have made a line break or are trying to support a team-mate in open play.