You need to research if you front derailleur will cope with the increased ring size of the Ultegra crank, this will be 30/39/52.
Also, you need to check the BB shell size, road are standard at 68mm, if yours has a 73mm, the Ultegra won't fit., Also, Shimano road cranks don't come with BB's so budget for this.
Would look at the gear ratios using a calculator (like this
Bicycle Bike Gear Ratio Speed and Cadence Calculator) to see if its worth changing.
If you FD can cope, the crank will run fine with 9 speed, even though it's spec'd as a 10 speed.