It's not a bad cooler, It's not a amazing cooler either. IMO it's doing just about what it's suppose to. You have to keep in mind that IVY is just a hotter cpu then anything else.
Muffins right thou, it's not water-cooling like the enthusiasts think about it. (which costs a lot :/) But you'll still get good performance out of it and your chip.
Also keep in mind... 4.2 Ivy = 4.5 Sandy. So your little dual core is prolly something equal to like 5.0 ghz at a 4.2 ivy clock. The chip is just a lot more efficient