The Economist itself is actually (slightly) more restrained:

A win, not a landslide

Nicolas Sarkozy's party gets a decisive majority in France's parliament

(Reuters)
IT WAS not the overwhelming victory predicted by the polls. President Nicolas Sarkozy nonetheless won a decisive majority at the second round of France's parliamentary election on Sunday June 17th. His Union for a Popular Movement (UMP) took some 323 seats out of 577, according to early estimates.

This was a slight dip from the 359 seats the UMP held in the outgoing parliament, and well below the 400-odd seats predicted by polling agencies after first-round voting a week previously.

 (...)

It is only the fourth time under France's Fifth Republic (after 1968, 1981 and 2002) that a single political party has by itself won an absolute majority. It is also the fourth time in two months that the French have handed a clear victory to Mr Sarkozy. This two-round parliamentary poll was a confirmation of the mandate he received at the presidential election in April and May.

The chief beneficiary of the swing away from the right between the first and second rounds was the Socialist Party. It took an estimated 206 seats, up from 149 in the outgoing parliament. The Socialists seem to have gained partly from a desire by centrist voters for a more effective opposition to Mr Sarkozy, after the collapse of Mr Bayrou's MoDem, which secured only an estimated four seats. They may also have been helped by fears about a steep rise in sales tax, which is under consideration by Mr Fillon as part of a switch away from heavy payroll taxes. (...)

Despite the undisguised delight on Socialist faces on election night, this poll was still a historic victory for Mr Sarkozy. The last time an incumbent political majority in France was re-elected was in 1978.

[How about 1995?]

(...)  

Armed with a decisive majority, President Sarkozy and Mr Fillon will now prepare for an extraordinary parliamentary session in July, a time when deputies usually head off on holiday. (...) With a handsome parliamentary majority, Messrs Sarkozy and Fillon will now face only limited opposition in parliament. Opposition on the streets, however, could be another matter altogether.