It's not very different from the Grand Cherokee They're very similar in many respects with the Commander having a bit more interior space and the 3rd row. With all respect to JeremyOG, I don't see paying the extra money (and gasoline) for the HEMI. The 4.7L does an admirable job towing on the GC. My cousin uses his GC to tow his Sport Nautique and you rarely notice it back there. I imagine the Commander will do a comparable job towing with that engine.
Personally, I wish they'd offer the Commander with the almighty 4.0L inline 6 but they don't put that on anything but the Wrangler anymore and it's going to be phased out all together soon from what I hear. The only 6 option on the Commander is the less than impressive 3.7L with the cheap rear end that couldn't tow my grandma in her wheelchair (not that I've tried).
When I can get a 2 or 3 year old used Commander, I'll probably be trading in my Cherokee (XJ) for it. I think it's a pretty sweet ride.