Blockchain.info has been buggy and slow for me.
Blockexplorer is completely unusable, as soon as i search an address, it shows an error that bitcoin-qt stopped working....
So now i'm using Blockr.io and it works great. Very fast, showing confirmations as soon as my bitcoin-qt does.
Nice advert
But indeed blockr.io is good
And when blockchain.info is down - I was using blocr