I asked myself that question rather recently too. I have a 2006 H3 with 96,000 miles on it. I bought her new and have always been happy and kept up with maintenance. Earlier this month the engine light came on, I thought, oh, time to change the belts and plugs and stuff like that. Mechanics came back with a "Low Compression in Cylinder 3" Ended up having to replace the Cylinder Head. I'll write up a longer story when I have time but the long story short, $2,300 lighter in the bank to fix that problem.
Since a few weeks have passed, I can look back and say I made the right decision. I still love the H3. It's been paid off for a long time and in the end even if I were to divide the $2,300 over the past 12 months, it's about $190/month. A lot less than a new car payment. If I didn't love my H3 as much as I do, I would have gotten rid of it when GM sunk the brand.
I agree with Mark. You could put aside what you would be paying for a new car and probably still come out ahead for maintenance.
Of course, the choice is yours.