Difficult question to answer that!
At the end of the day it is a Toyota and the new IS250 is still a Toyota and people will always say that. Lexus or not the parent company is Toyota.
Mine was bought on value for money, spec and being different, I would have definitely bought it even if it was a Toyota, especially as I also looked at the Celica.
To answer the question where £22k justifies a Toyota IS200, well what about the Celica ST for £23k and the great Supra for £30k+ !
Funny thing is, Toyota dealers wont touch it with a barge pole as far as servicing goes, well my local ones anyway. Something to do with Insurance purposes.
Bet servicing would have been cheaper if it was branded Toyota though!