Well I believe it differs from person to person for me the IR was easier than normal flying the computer does everything for you, the only thing you have to do is know how to read your chart and put in proper data into the aircraft. It shows you what altitude you should be on when you are on track everything. The only approach where you have to think is the VOR since you need to know/perform your rate of descent properly (with RNP or ILS the aircraft show you if you are in the correct position) + the holding patterns so you perform the correct entry and holding. The rest is much easier than VFR flying especially the landing when you have extremely long final.