I assume you've already googled it and just want personal experiences. I use it all the time. Not had any problems. Pretty comprehensive to use. Functions are useful eg for quickly measuring heights of candles or distances between highs and lows. Trailing stops work well (although MT4 needs to be running as it's a client-side trailing stop order). Can code it using a simple language so if you can program, then creating your own indicators etc shouldn't be a problem.
The PDA version is a bit buggy, IME. Ended up switching off bug alerts as it was annoying me.