Little errors aside, this is pretty damn good english. Be careful with colons and semicolons. I know their usage can be subtle.
Jesse (Edits follow)
It was the worst experience in my life. The more I think about it, the happier I am to be at home
Tom is the tallest of his brothers, although he is the youngest
Weíd better not go to that restaurant (Letís not go???. to that restaurant) .They say it is the most expensive in town. Letís choose a cheaper one.
That painting is by Modigliani (one ofModigliani's ????<this could also mean Modigliani owns it, which is rarely the case, but it is still correct and understandable>). The woman has a long neck and a sad expression
<so close!>That holiday will cost (is it the right future form??<yes>) her 600 euros a day, but she is a writer and can affort it!
He is not as good at English as everybody thinks; his latest translation was the worst of ( in??<yes, 'in' is okay as well>) the class.
Tom and Jack are friends. The former is an upholsterer, <and> the latter is a plumber. Tom earns as much as Jack <but / however> Tom spends more than Jack because he goes on holiday two months a year.
John is less of a squanderer than Jack is: <he is saving because> he wants to buy a house in the country.[/QUOTE]
Student or Learner