Micro Converter with ADC/DAC peripherals
The name is a clue. "Microconverter". You can consider this an ADC/DAC with a microcontroller peripheral attached rather than a microcontroller with peripherals. The (semiconductor) process used is more optimized for precision analog than trying to fit analog bits into a digital process and ending up with mediocre analog performance. For example, the reference has a tempco of 15ppm/K (typical) and is accurate to +/-0.4% maximum. Not great numbers, but better than most of (say) Microchip's offerings. That said, this is a very old chip (over a decade, IIRC) and each year the cheap/high volume ones tend to get a bit better. 

So the main difference is the performance of the analog bits- reference, ADC and DAC will be closer to that of similar discrete devices (they're made by a company known for analog prowess). 

You can also get models with "24-bit" ADCs, and an ARM core. 

The advantage of having several chips combined into one are less board space, easier to get going, less parts on the BOM. Disadvantages are that the cost will probably end up higher, and the performance lower than a solution designed with separate chips. If the chip gets discontinued and you've designed a product (or an entire product line) around the chips, you may have bigger problems than if you went the other way.