In short. If trading is active, like today, how can we find out about current BTC price?
1) Current, highest and lowest prices displayed at our trading screen at MtGox itself - have only very little connection with reality (a blatant bug BTW, which is there for months)
2)
http://mtgoxlive.com/orders - stops working from the slightest breath of wind
3)
http://bitcoin.clarkmoody.com/ - is not able to connect to MtGox when trading is active, although continuous reloading of the page helps a bit
4)
http://bitcoincharts.com/markets/ - doesn't provide realtime data
So, OK, lets place an order being blindfolded. If we are lucky enough, it will take only 5 min for the order to reach the order book. The same if we are canceling an order. The same if we work with the exchange through https API (may be websockets API is better, I don't know, but that's highly doubtful).
Additionally, IMO, a serious exchange should provide normal (not web) SSL sockets API.
It doesn't seem that MtGox improved even a little bit during last several months.
I hope some other exchange, a reliable one, able to handle high liquidity, will emerge, and that liquidity will go there from Gox. Currently MtGox sucks.