The Ioniq Plug-in has some limitations in that it relies on waste heat from the gas engine for cabin heating and it's motor is limited to 44.5 kW (60 HP). The original Prius Plug-in also had no electric and had motor output limited to less than 38 kW. The new Prius Prime plug-in can do up to 68 kW (91 HP) from its battery pack like the Ford Energi models. The Chevrolet Volt can do 111 kW (149 HP) with 0-30 mph nearly as fast as the original Model S60.
The Ford Energi models are somewhat less efficient and can only do around 20 miles of electric range with a 0-60 mph of about 15 seconds in EVNow mode or 7-8 seconds with gas engine assist. The Ioniq Plug-in does about 27 miles and any 0-60 time kept all-electric would probably be 20+ seconds or maybe 9-10 seconds with gas engine assist. The Volt is EPA 53 miles and does 0-60 in about 7.5 seconds either all-electric or in gas burning mode.
The Ioniq is likely competitive with other 20-something mile range plug-in hybrids depending upon final pricing which has not been revealed yet. Among the 3 Ioniq variants, it probably has the weakest marketing story versus its competitors.
The plain Ioniq hybrid is significantly cheaper (if you don't want to pay for advanced camera and radar-based safety features) and gets slightly better gasoline EPA ratings than the Prius and other competing hybrids.
The Ioniq Electric has nearly the highest range of the sub-200 mile range cars with 124 miles and the highest efficiency at 136 MPGe and includes a heat pump system to stretch the miles during the winter. It also charges faster, at up to 70 kW, than any other non-Tesla electric car when the new CCS stations begin showing up later this year.
The bottom line for plug-in cars is that the Volt provides a much better electric driving experience while still providing full-performance extended range for road trips in areas with poor DC charging coverage at 42 mpg.