I have had some problems loading since they revamped the charts about a month ago, but I have attributed it to my lack of RAM. I have been very happy with AMTD for about 2.5 years and I'm just now exploring other brokers because of execution needs.
My only issue with them is that when I started trading large volumes (say .3% of average daily volume), I couldn't execute a limit order without the market moving away from me. Also, their system tends to have some glitches in account value calculation and order status at market close.
The tools are phenomenal for a swing trader or small time daytrader though.