I have driven the X3 2.5. The car still considered new (about 7 months) because don't drive that much. So far no problems for me.
The X3 is a good car to take for long distance trip. Good looks and very safe car. The high seating position makes it easier to spot dangers earlier. I drove it to Terengganu and Penang. Very comfortable and with this car you don't really notice the bumps and uneven roads on the highways compared to my E46. If you drive the X3 on the ELite highway going to KLIA at high speed you will know what I mean.
The car is agile and feel very dynamic compared to my father's Mercedes E240 which feels like a big elephant. The car does not feel big. Road holding is very good even better than my E46 318 as the X3 rolls minimally compared to my E46. On my kuantan trip pass by karak highway - very good cornering and road holding ability. Just feel superior than my E46 318 with stock specs. Must be the xDrive feature but me being an amatuer dun really know how to quantify or put it in technical jargon. Just feel X3 more stable in corners with precise steering. Maybe some experts can contribute here.
Plus not to mention the well designed cup holders (some may disagree since when the passenger side cup holder is extended it block the air cond vent) but is better than some other cars which blocks access to the radios and center controls when extended.
The compartments and the cargo area securely holds my mineral water bottles and snacks haha, important features on long distance trip esp on country roads. You don't want your mineral water rolling around in the boot.
The bad side of this car is the aluminium trimming on the door for the 2.5 model looks odd and basically the interior look a bit cheap.
The engine i believe is the old engine. The rated power output is about 192 bhp. The new engine would have more power.
Therefore the car power to weight ratio is probably the same as my 318 2.0 liter. I found out the sad way that the X3 cannot overtake a proton Gen 2 1.6l ( I think) easily. But most SUV are like that. So if you are looking at performance you should consider a 3.0 liter but at that price I might as well add more $$$ to buy an X5.