I purchased the 6cyl Mustang in 06 at 73,000mi as my first car and drove it about 13,000mi. It broke down twice, both times due to the alternator. The second breakdown was because an old alternator had been used to replace the first one and based on what I've read reliability doesn't seem to be a common problem with this car. Other than that I really enjoyed the car; the V6 had adequate power, although I would recommend the V8. I found that careful driving could get about 20mpg out of the automatic V6; I'm sure a manual could be fairly economical. The car was fun to drive on short trips, and I never noticed any issues with comfort on longer drives. I would recommend this car to anyone.
Everybody always liked this car. It had a classic name that everyone was able to relate to and I liked the looks. It was great value for the money and didn't kill me on gas. When it did break down it didn't cost a fortune to fix and even the 6 cylinder was surprisingly fun to drive.
Plastic parts were my biggest problem. The exterior plastic was discolored and faded when I purchased the car, and interior plastic parts were falling apart when I sold it; not surprising for the age of the car though. Doors and interior parts also squeaked and rattled throughout the time I owned it.