Well even with over 100k on the clock, IS like most Toyotas will be solid as rock if properly maintained.
One thing I would do, assuming that you just got the car, is to check if you had the Timing Belt changed. If not than I would do that soon, and that will probably be the biggest expense of them all. I know if the dealer did the T.Belt they usually put a sticker on the T.Belt cover with date and milage of the Service, so that's should be easy to find. Than I would look into all the fluids, mainly Trans. Fluid, Get that flushed or get the pan dropped and cleaned would probably be a better option. Next on my list would of been Engine Coolant, do that as well. Those should be the Major things that you should look into doing ASAP in order to help the car perform and last for long time to come. Also check the Air Filter. There are other things that you might look into but I would do the things that I mentioned first.