A dog can definitely give you a lot.
The more you give it and the better you treat it the more you'll get in return.
I had my Jack Russell cross Jessie for 13 years, died in 2012. Still miss her loads.
Like someone said once, buying a dog is investing in a tragedy.

Wouldn't change it though. If you know for sure that owning a dog will fit in with your lifestyle then go for it.