Bonn is nice and beautiful but very quite and you would not see many people around... I have lived in bonn for 5 months until Nov 2011 and have been in Cologne since then and can say that Cologne is RoCkInG!!
I was in Bonn recently and I found this to be a beautiful town. Although it was the capital of Germany for a long time, the city still has retained its charm and a small town environment. Its university campus is beautiful. I also liked the city square. The current Pope worked as a Professor in Bonn. Beethoven House is beautiful. The tallest Post Tower,’ is the headquarters of the Deutsche Post AG and DHL. The food at Ristorante Grand' Italia situated along the Rhine was delicious and tasteful and one of the best compared to many of the restaurants. I also found people to be very polite and courteous. I would recommend to anyone, who is visiting Germany to visit this city, which is not too far from Frankfurt. It is about an hour and 30 minutes train trip from Frankfurt. I also found it to be convenient to take the train right from the Frankfurt International airport. I would love to visit this city again sometime in the near future.