I've been told the newer IP models have been improved. I have a 3 qt Duo Plus bought to replace a crockpot but it only cooks from the bottom, and the High on my IP is the equivalent to med or low on most crockpots. Some things to know to get the most out of your IP when used as a slowcooker:
1. It will take longer than a crockpot, add 15 - 30 minutes for every hour of cook time.
2. When adding ingredients use hot water and other preheated ingredients if possible.
3. Heat everything on Sauté and bring to a full simmer before switching to slowcook. (This can take 30 - 60 minutes if starting cold.)
4. In order to actually COOK your food, you'll need to use the High temperature on slowcook.
5. Use a glass lid with a vent hole instead of the IP lid so you can monitor your food without losing heat by taking the lid off. (A glass lid from one of your stove top pots or pans should do the trick.)
6. If you're running short on time and food isn't done yet, you can always switch to sauté and finish cooking that way.
Once you know what to expect and how to improve the performance it makes it a better option to use.
For reference: I made crockpot eggplant parmesan as my first IP slowcooker meal before learning the tips above. It normally took 4-6 hours in the crockpot. I had it cook overnight for just over 8 hours and still had to switch to sauté to finish it. It's not a dish that translates well to pressure cooking because of the tomato sauce and parmesan in it. Next time I'll know better and do better. I'll also be prepared for the longer cook time.
Hopefully this helps and lends a little insight. Good luck with yours!