As (seemingly) one of the few on here to have actually attended the Olympics I feel well placed to offer my opinion; I thought the checks were-
a) Necessary - we have a terrorist threat in this country as we well know and they'd have loved nothing more than to put themselves on the map by ruining this event.
b) Reassuring- Nothing fills me with more pride and makes me feel safer than seeing the SO19 boys with a big weapon. As you came off the train you could see them on the tops of tall buildings, they were almost saying to the terrorists "make my day".
c) Efficient- The bag checks were handled by our fantastic armed forces, they were polite and quick, we queued for less than 5 minutes to get through this part of the iron ring formed round the Olympic Park- it meant that once you were inside you knew everyone has been checked and was 'safe'.
All in all it had to be this way as it would have only taken one rogue bomber boy to expose a loop hole in the security plan and our government would have been pounded for it internationally.