Why do things smell good while cooking but have little flavour when finished While cooking, particularly things that cook slowly on the hob, it smells really good while cooking but when finished it never seems to have as much flavour as I hoped.

Am I doing something wrong or does this happen to everyone?
There are two components to flavor: aroma and taste.  The wonderful smells you get are the volatiles of the ingredients you have been cooking, and while they add a lot to dishes, aromas are just part of what makes food enjoyable. One also needs to worry about taste, and that may be the missing part.  When I decided to improve my cooking three years ago I was mystified by flavors.  I wanted to know how spices worked and how to use them better, but all the reading and experimenting did not help my cooking.  

Then I learned the Remick Maxim (lower the temperature when possible) and the quality of what I made went up more than in the entire previous year.  I then heard Thomas Keller speak about salting and things clicked.  One has to get the salt, acid, and sweetness of the dish right or everything else amounts to nothing.  Once I learned to pay attention to taste, spices became easier.

The next steps have been:


Understand caramelization (the Maillard process or reaction), it is a great source of flavor.
The main ingredient needs to be rich in flavor. Even something as simple as rice will make a difference.  Try making rice with Basmati from India or Pakistan, where they age the rice before selling.
There are a lot of underdeveloped recipes out there.  Beware.
Use spices in groups that traditionally grow in the same region.  Cumin and coriander, basil and thyme.