Training and intelligence
Border Collies are very intelligent and very trainable. However, the key here is finding activities to use up both physical and mental energy, so the dog is happy and has no need to think up ways to amuse itself. For anyone who wants to compete in obednience, few breeds can beat the Border Collie for willingness to work and speed.
Border Collies are born to herd, and even with no sheep to look after, they are still driven to be active. They are very devoted to their family, and excel at obedience and agility activities. They can be very focussed on what they want to do, and can be very effective in communicating what they want you to do.
Attitude towards strange dogs and people
Not having a high level of agression, Border Collies are usually friendly with other people and most dogs. They do have protective instincts, and some can be shy, so socialisation is important.
Grooming and shedding
Border Collies are medium shedders, and a weekly groom will help keep the coat tangle free.
Border Collies have very high energy levels, and need a lot of exercise. Occupying them adequately is quite a challenge as they have energy, stamina and are very clever. Don't underestimate the commitment you make in taking on a Border Collie; significant amounts of exercise will be necessary every day no matter how tired or busy you are, or how bad the weather is!
Need for company
Border Collies are not couch potatoes, and the only thing worse than lounging around, is lounging around alone. They need company and will not take well to being left alone for long periods as they will become bored and destructive.
The huge popularity of the Border Collie breed shows that the effort you need to put in to keep this breed happy is well worth it. Remember their breeding though, which often results in them trying to herd their people, especially children.