Just bought a 2010 Model 3

There is a thread in the Prius III accessories forum called "what have you done to your Prius today". It's a looooong thread but there are a lot of good ideas. I'm getting a 2010 Prius in the beginning of August but so far on my to do list is tint windows, all weather mats, change out horn, add HID lights.

 

The Prius has many 'infotainment' displays but is short on 'car guy' gauges or technical hybrid data. You may wish to add gauges. I use a Scangauge II, it allows 4 of 37 built in gauges to be displayed, you can add 'xgauges' as well, there are over 100 of those, so you can get all the detail the Prius really knows. It also allow programming some computer parameters and reading some fault codes, it is very nice.
PriusChat Shop : ScanGauge II Scan Tool + Digital Gauges + Trip Computers [ScanGaugeII] - $159.95

There are other commercial gauge packages as well, I have not heard as happy users of them.

There are PC and Android apps that can use that hardware with a bluetooth ODBII adapter, that are considerably cheaper than the scangauge.
Prius OBDII Third-Party Apps | PriusChat

If you do not find yourself needing any more gauges, do not bother. But if you keep wondering 'what is really happening' these are good answers to your curiosity.