Car is very cool. In my 9 months of ownership I haven't had one single issue.
The first 5 services visits are FREE.. yes, FREE. That includes oil changes (unknown if this holds for 2004). Although you may have to point this out to the dealer doing the service. Prius has its own maintenance manual, make sure you don't get the generic Toyota maintenance manual. (Toyota dealer ratings can also be found at the link below.)
You can't talk Prius without mentioning "stealth". Stealth is when the car goes on electric/battery only. Typically you can get it in stealth on the flat going up to about 40 mph (miles per hour). A heavy foot will engage the internal combustion engine. Parking lots are great for stealth mode and some folks have expressed concern because pedestrians won't hear your car. Don't assume pedestrians are rude if they don't move out of your way. The engine also shuts off when coasting downhill (and generates engery for the battery) and when at a stop.
Cool note: When in park you can't rev the engine. You can step on the accelerator, but it won't do anything. Don't forget the ready light being on means your car IS started but you aren't spewing emmisions (or using gas) by sitting and idiling.
Truck has more space than my Lebaron Convertable did. Actually, much more.
The Prius is a clean car. In my city we have smog alerts every summer, this is one of the ways I do my part. The milage the Prius gets is secondary to its cleanliness. In the winter the engine will run to warm up the catalitic converter (and, consequently, use more gas).
Someone expected it to meet EPA milage numbers? I don't know a car that does. That is best case. All cars depend on where you drive and how you drive. The Prius is like other cars in that case. Your milage will vary. My current average in 9 months is somewhere about 45 mpg (mixed driving, mostly winter at this point).
The 12 volt battery (not to be confused with the hybrid battery) is small because it only boots the onboard computer, no starter! There have been some reports of batteries that were damaged on dealer lots and people had problems with them, they WERE replaced under warranty (or they should be). Any car you let sit the battery will go dead. The Prius is no exception and because of its small size it may happen sooner. With a good battery many people have gone on trips and let the car sit unattended for several weeks without any problem.
It carries a 8 year 100,000 mile warranty on the hybrid components of the car. There have been 0 reported failures of the hybrid battery.
On 2003 and earlier models Toyota recommended tire pressure is too low. I run mine at 48 front and 46 rear. This helps with the wear of the tires which has been a reported issue. The cold rated pressure of the tires is 50 psi so this is not going over the recommended safe cold pressure for the tire. Once your orignial OEM tires there are other options for tires mentioned at the two links below.
Acceleration and speed are more than adequate. This car is not underpowered. The engine is prevented from over revving so it will never redline (if you had a tachometer). When accelerating you will hear the engine working, this is normal and not a concern. Go ahead and floor it (but expect it to hit your milage as with any car, you'll just SEE it).
The 2004 model coming up has improvements over the earlier model. The AC is electric so the internal combustion engine doesn't have to run when you are running the AC therefore your gas milage won't take as big of a hit.
The 2004 is bigger and a hatchback with better gas milage! Wow. I'm going to be test driving one but I probably won't trade in my 2002.
If your looking for owners opinions I recommend this link:
http://autos.groups.yahoo.com/group/toyota-prius
For extensive information about the one owners experience check this link:
http://john1701a.com
2 year update...
Still love this car.. still no problems (not even minor) after 2 years.
Amount Paid (US$): 20500
Condition: New
Model Year: 2002
Model and Options: Daytime running lights, cruise, side air bags