I was shocked when i found out about the run Manchester are having in the last 2 years in CL.
They aren't defeated for exactly 2 years, after the CL semifinal defeat at San Siro in 2007. In the following 25 matches no-one managed to beat Manchester United. This is an all time CL record.
In the meantime Manchester won the CL once and made it once more to the CL final, with a chance to win it again and make another CL record because no-one won the CL (not counting the champions cup) twice in a row.
Their defensive record is just as remarkable. They conceded only 12 goals on these 25 matches, and only 5 goals in the knock-out rounds even though they played against the best teams in the world (Chelsea, Barcelona, Inter, Arsenal etc).
Comparison can be made between this ManUtd and two other great teams from the previous decade: Capello's Milan (1993-1995) and Lippi's Juventus (1996-1998). Milan and Juve made it to the final 3 times in a row, but Milan lost 4 and Juve lost 8 matches in the process, while ManUtd are yet to lose a match.
Only regarding the conceded goals Capello's Milan is better because in 3 seasons they conceded only 10 goals and only 2 in the knock-outs (both times in the CL finals).
To make it short, i think it's safe to say that this Manchester United made it to the best 4 generations in CL history together with Milan of 1993-95, Juve of 1996-98 and Real Madrid of 1998-2002.