The only "hatred" is here on Answers from a few trolls. In real-life it doesn't exist. I have both a 2001 and a 2004 Prius which have been great low maintenance, reliable, and fun-to-drive cars.
1. You should purchase a car because you like it. All cars are an expense--some are just a lower expense then others. My 2004 has cost 12 cents per mile for dealer maintenance, tires, and fuel combined over the 130,000 trouble-free miles I've driven it so far. My wife doesn't keep a logbook for the 2001 but the costs appear similar. Both still run like new.
2004 Prius MPG from the logbook. (Complete years only):
2003-2004 -- 50.8 mpg 17,628 miles
2005 -- 52.6 mpg 14,688 miles
2006 -- 56.3 mpg 16,174 miles
2007 -- 57.3 mpg 18,384 miles
2008 -- 59.9 mpg 21,755 miles
2009 -- 61.4 mpg 16,177 miles
2010 -- 65.2 mpg 12,134 miles
2011 -- 66.9 mpg 11,272 miles
2. The so-called "hybrid premium" on the Prius is about $500. The remainder of the difference in cost that you read about is because most reviewers compare a sub-compact or compact econo-box to the Prius. The Prius is a mid-sized car with a lot of premium features standard. Mid-sized cars are always more expensive than econo-boxes.
3. The number of batteries that have failed are very few. Even the 2001-2003 Prius with the older style battery typically get 200,000 to 300,000 miles or over ten years of life. Based on the posts in the various Prius groups more than half are still on the original battery. From the 2004 on there just aren't enough failures to be even worth counting. The battery is really a non-issue for Prius owners. And there are several choices:
A. Purchase a new battery for less than $2000 from a dealer (plus $500 installation).
http://www.trademotion.com/parts/2009/TOYOTA/PRIUS/?siteid=213747&vehicleid=1443574§ion=HYBRID%20COMPONENTS
B. Purchase a reconditioned battery from a company such as http://www.reinvolt.com/
C. Purchase one from a recent wreck for about $500.
Really there is no more reason to worry about the battery than there is about the transmission in an old fashioned car.
4. Toyota has removed many of the parts of a conventional car from the Prius and replaced them with more reliable electronics and has simplified others. For instance the Prius doesn't have: an alternator, a starter motor, a serpentine belt (2010+ only), a clutch or fluid coupling. In addition the automatic transmission with it's hundreds of parts has been replaced by a simple planetary gear system similar to a differential.
http://www.ctvbc.ctv.ca/servlet/an/local/CTVNews/20110125/bc_olsen_prius_reliability_110125/20110125?hub=BritishColumbiaHome
As far as the Navigation system goes, many people don't like factory navigation. Basically the pros are:
1. It's always there.
2. Not a real target for thieves.
3. Won't be left in a hotel room
The cons are:
1. Expensive.
2. Doesn't always have the latest features.
I like the Nav system in my 2004 but I supplement it with the iPhone.
The keyless entry system is one of those things that you think might be a toy--until you have one. Then it becomes something that you won't do without if you can possibly afford it. The two big advantages are:
1. The fob is always in your pocket so you never set it down in the trunk and close and lock the trunk.
2. You don't have to juggle whatever you're carrying to open the door.
I don't know of any disadvantages other than it adds to the price of the car.