It's hard to beat the Prius. My 2004 has cost 12 cents per mile for dealer maintenance, tires, and fuel combined over the 115,000 miles I've driven it according to the log book I keep.
To cover your points:
1 & 3. Lifetime average has been 57 mpg over 115,000 miles.
2003-2004 -- 50.8 mpg 17,628 miles
2005 -- 52.6 mpg 14,688 miles
2006 -- 56.3 mpg 16174 miles
2007 -- 57.3 mpg 18384 miles
2008 -- 59.9 mpg 21755 miles
2009 -- 61.4 mpg 16177 miles
2010 -- 65.2 mpg 12134 miles
2. MPG on trips is good. It's hard to get under 50 mpg. on a trip. Here's data from my last trip.
Date________ODO_____INC____MPG (l/100km)
08/13/10____111690____625____59.8 (3.9)
08/14/10____112308____618____60.0 (3.9)
08/20/10____112972____663____64.2 (3.7)
08/22/10____113411____438____58.9 (4.0)
08/31/10____113922____510____61.8 (4.0)
4. It's roomy because it's a mid-sized car and holds four full-sized adults.
5. The insurance is about $500 per year in a big city, but then insurance is mostly about the driver unless you're driving an exotic. It's been totally reliable and trouble-free. The only car that should even come close is the Nissan Leaf, and it's not under $25,000, plus it won't work for long trips.
6. The base models are under $25K.
7. Only use regular gas in the Prius.
8. Speed is really no problem in the Prius.
About the acceleration. Some folks think that the acceleration is poor because the zero to sixty times look a couple of seconds slower in the reviews. This occurs because when reviewers do the zero to sixty test they rev the engine and pop the clutch (or the automatic equivalent). Seldom are those vehicles actually driven that way in practice--even by the most aggressive drivers. The Prius won't let you do that kind of juvenilia so the times look slower. In addition:
A. Many people are used to using the engine sound to tell when to back off. In the Prius the engine speed is only loosely coupled to vehicle speed so when they hear the engine rev they back off--resulting in slower acceleration. Because the Prius doesn't allow the engine to be over-revved there is no need to back off.
B. Because the Prius never shifts, there isn't that low-gear jerk to ten mph when starting (followed by rather anemic acceleration in most family sedans). Instead the Prius accelerates smoothly and quickly right up to the maximum allowed speed of around 105 mph.
C. The approximately 195 ft.lbs. of torque that the larger motor/generator provides is available at all speeds so acceleration from highway speeds is very good.
D. The Prius is a family sedan, so if you're looking for a Porsche, you are looking at the wrong vehicle. Having driven both there is no question about which one is more fun to drive (hint: it's not the Porche unless you only drive on the race track).
9. Here's something about reliability. I have both a 2001 and 2004 and they've been trouble-free and low maintenance.
http://www.ctvbc.ctv.ca/servlet/an/local/CTVNews/20110125/bc_olsen_prius_reliability_110125/20110125?hub=BritishColumbiaHome
Note that only non-Prius owners have complaints about costs. As far as I can tell, this is just "sour grapes".