Nothing thus far, other than the genius I bought it from had applied wax to the car, but failed to remove it. He drove it around for a week, sitting in the summer sun. Obviously it ruined the clear coat.
I serviced everything when I bought it... meaning spark plugs, fuel filter, oil and filter, air filter, MAF sensor, etc. Went from getting about 26 mpg to around 32 mpg, but the 0-60 time was unreal. Went from high 8 seconds to high 7 seconds.
The headliner is peeling in one spot, and the sun visor cloth is virtually non-existent.
The valve cover gasket was leaking when I bought it. I didn't replace it, just removed it and cleaned the gasket and mating surfaces. It was leaking due to the same genius that waxed the car. He over filled the engine oil by at least a quart.
I did quiet a bit of research before I came around to buying this car. I wanted something fast, economical, and reliable. I have had no worries or problems to date, though to be fair I've only put 15000 miles on it.
The car is flat out fast for what it is. It's not gonna hang with GT Mustangs or anything, but if you keep in mind that it's a Ford ESCORT that I have a total of < 2000 dollars invested in... well it's just flat amazing.
I've done a couple of... er, "upgrades". Let's just say I can eat any stock Civic Si built before 07'. Even against the 07 Civic Si it's a drivers race, and I've invested no more than 250 bucks in "upgrades". There's a lot you can do to this car yourself, without spending a bunch of money on parts, to make it faster. Right now my 1/4 mile trap speed is 92 mph, doing 0-60 in an average of 7.35. Land missile? No, but quite impressive considering how much I paid for it and how little it drinks.
On to economy. I bought the car for 1600. After taxes and a few performance parts (some of them bought from Lowes Home Improvement!), I have < 2000 dollars in it. Not bad.
It's cheap to insure. Really cheap. It was never really considered a "sports" car, it was lumped into the other Escort class. Fine by me. The greatest part of all... I get 27 MPG if I drive the thing like I stole it. Driving like a normal human being usually nets around 30-32 normal, and 38 or so freeway.
Finally... reliability. I haven't logged in enough miles to be a fair judge of reliability, but the car had 140000 on it when I bought it. That tells you a little something. I can turn a wrench, and the point of me buying this was cheap speed, so I don't baby it. I drive the thing like I stole it. If I tear it up, I'll go to the local pick and pull and get a second hand tranny. This is my toy, plus it saves me about 200 dollars a month over driving my truck everywhere. It's already paid for itself. Sweet!