Thanks, yeah that'll be an early Mk4 (pre-facelift). In that case, the 1.5 EcoBoost is probably the best engine choice in those. They're 3 cylinder, which gives them a slightly different sound, but they're generally very reliable, more so than the older 4 pot in Mk3s. Plenty of torque too, I had the 150 version and didn't find it lacking. MPG wasn't quite as good as I hoped, in the high 30's.
At that age it'll still have independent rear suspension which is a major plus point for both ride and handling. STLX gets sports suspension and large wheels which can reduce the comfort a bit, depends what you're used to.
By far the biggest issues with the Mk4 are the battery charging (or lack of it due to tight emissions regs) - factor in a battery replacement soon if not already done. Can't think of anything else major to check on these. Worth checking for any water leaks and making sure the AC is ice cold.