I don't think many are really disapproving but the signing of Mertesacker does smack of Wenger going for the cheap option. Jagielka was clearly our first choice target this summer & last summer, we didn't sign him because we weren't prepared to pay up. It seems Cahill was our second choice, again it seems we weren't prepared to pay up.
It looks as if Mertesacker was third on the list and we signed him because he fits into Arsene's fair valuation of a player.
Mertesacker is a good player, I do have doubts about his lack of pace, and he's not playing at the level he was a couple of years ago but he'll improve our defence and has the potentially to form a very good partnership with Tommy V.
I think that's an excellent post, like you said the cheap option once again.
Really not convinced with this guy but we shall see.