I have owned many cars and each time I always choose a different brand. Prior to my is220d i had a volvo s60 t5. Nit quite the comparison you want.
I would say that on looks you can get very subjective - personally i would put the exteriors of each cars equal. And quite a few japanese cars are getting the is220 look.
Inside - well the dash on the lex beats the volvo hands down, especially when you have the toys fitted. The volvo always looked like it was made of bits and you could see the joins on the bits.
However the volvo is way more confotrable than the lex, in terms of cabin noise, seats (oh how i miss those volvo seats) and space. The s60 wins hands down on space. In that my wife could easily turn around and help the kids out in the back (picking up tous etc). In the lex, no way.
Also i really miss the volvos ability to fold flat the rear seats. And dont forget the volvo also lets you fold flat that front seat for extra long loads. In the volvo i never had to worry about going to ikea. in the lex itw always a 'will it fit' question.
The lex dash creaks a fair bit, never had that on the volvo. I know people say the lkex sound system is great (you can fit an ipod no worries) but i had the upgraded volvo sound system and it kicks the arse of the lex.
Reliability - well after 3 months of ownership my lex had the dreaded dielsel problem and was of the road for a month until the part became available. It broke down twice prior to this leaving the wife stranded on the motorway a couple of times. I will never go in the lex without a fully charged mobile. I never had an reliabaility issues with the volvo - i suppose thats what you get for buying an older car were he problems are itoned out.
There are reports of the lex dielsel suffering the same dreaded coking problems as the toyotas, search this forum for auto express and you will find the thread.
I have said this before, but out of all the brands I had, the volvo is the one i will be returning to.