what are the limitations of freundlich adsorption isotherm?

freindulich adsorption isotherm is a graphical representation of conc of adsorbate vs pressure ..

Its only valid when log x/m is plotted in y axis and log p will plotted in x axis and a straight line will come,,

where x refers to the mass of adsorbate and m referes to mass of adsorbent/...
it fails to explain the nature when the pressure is too high and also the temperature is too high..
besically the graph concludes that for a physical adsorption when we increases the temp then the rate of adsorption will decreases..

the equation is 

x/m=kp^1/n
HOPE IT HELPS
CHEERS