Biacore systems characterize molecules in terms of their:
specificity of their interactions
on and off rates (kinetics)
binding strength (affinity)
The systems also provide sensitive, accurate concentration measurements. This is based on the ability of the biomolecule of interest to interact with a specific binding partner, and may therefore be more informative than generic measurement techniques (total protein concentration for example).
No other techniques can provide such comprehensive information in real time, without the use of labels and in one system.