Well, we've put nearly 2000 miles on the Prius (Patti Prius, the kids named her) so far and it has certainly proved itself as a gas miser. We're averaging about 47 mpg for our combined city/highway driving so far. That's a big jump from the roughly 22 mpg we got with the RL in similar driving conditions.
The Prius is more comfortable and roomier than we expected. We took a long trip to NY this past weekend and everyone was fine. There was plenty of room in the hatchback for luggage--probably about the same as the RL.
The electric motor is great around town. When we're driving more than 10 minutes we generally get about 50 mpg around town. The Prius is a star in stop and go traffic--all that braking generates electricity to recharge the battery, and in slow traffic much of the power comes from the electric motor.
On the highway, the Prius gets a bit lower mileage--about 45-46 mpg--but that may be more a function of the Curmudgeon's lead foot.
We're still getting used to the navigation system, which is not nearly as simple or intuitive as the Acura one, but certainly adequate to get us around. (For some reason, it wanted only to take back roads to NY; no doubt we selected some arcane option by accident.)
One very annoying factor on the Prius, however--at least on ours--is the gas tank. It registers "full" when it is still at least 2-3 gallons short of being full. Trying to get it to finish filling is a real chore. Yet, driving around with only 9 gallons in an 11.9 gallon tank partially defeats the purpose of higher gas mileage (i.e., a longer cruising range). We're going to explore how to fix this particular problem.
Another annoyance is the climate control system. When we set it to "auto" at a certain temperature in the dead of winter, it insisted on running the air conditioning, robbing us of fuel economy. There's also no indicator for engine heat, so we don't know when the engine is warm enough to turn on the heat (on low--again, the higher the fan, the lower the fuel economy). We'll be interested to see how much fuel economy we lose in the summer when a/c becomes a must.
The Prius has a high profile, with a narrow wheelbase, and in high winds you can definitely feel it, whereas the all-wheel-drive RL was a road hugger.
On the other hand, some features on the Prius work better than on the RL. We tried to program the RL so that all the doors would unlock when unlocking the drivers door, to no avail (although it's supposed to be able to do that), but had no problem with the Prius.
The RL also had super-sensitive doors that were always closing on people when you didn't want them to--not a problem with the Prius.
All told, we're satisfied. It's not a good-looking vehicle. But it gets us around town without destroying the planet quite so badly. And, we hope that by the time we get around to our next car, we'll have plug-in hybrid options with gas mileage in the 80-100 mpg range.