BQM53

Too deep?  

HolIgor: It seems that that marked stone was well placed. It is difficult to catch as White's groups on both sides are not very thick.

Wrong peep?  

Things got hairy after this, although I did live everywhere. Should the peep sequence have been something like a, b, c?

HolIgor: I think 3 is the wrong direction here. After 1 White's upper group is rather stong. The general rule is to attack from the side of the weak group. If, instead of 3, White plays from the other side, a moyo starts to form little by little on the right. White will have good compensation.

Bad aji  

There is a useful sequence here for Black, suggesting that in this case the marked white stone fails to be good shape.

Charles Matthews

Why not...  

I don't know - White's not strong enough to make the invasion completely suicidal, but it seems in a better position than Black... why not just go for the direct pushing approach?

After 7 (assuming I somehow analysed correctly), I don't think Black can get an eye there, and in any case, White looks like she's going to get a pretty solid wall by the end of the exchange.