Christie has NOT helped NJ's economy, he has hurt it. During his time in office, NJ has done LESS well in recovering than the nation as a whole. A fair test of how he is doing would be to compare NJ with a similar Democratically led state.

NJ is an affluent state with an abundance of jobs in R&D and in Finance. It is also a state where high school kids are among the top performing in the country. It also has a significant number of older urban centers that were once successful cities. Another state that could be described similarly is MA.

Since Governor Christie was elected in 2009, you can think of these two states as if they were testing the republican and the Democratic economic solutions. The unemployment rates are from the Bureau of Labor Statistics.

December 2009 (a month after Christie was elected - as a baseline): NJ - 10.0 MA - 9.3
December 2010 : NJ - 9.1 MA - 8.2 (Note, at least in NJ, the budget was passed in the fall of the previous year - so this year is not yet affected much by Governor Christie. MA and NJ are moving pretty much in sync - though MA is doing slightly better.)
May 2011: : NJ- 9.4 MA - 7.6 (This year it is a Christie budget and Christie is in charge - and while MA continues to improve, NJ gets somewhat worse.)
December 2011 - the most recent I can find - NJ 9.1 and MA 6.9.

There is NO way to look at these numbers in Christie's favor. It is often said that the states can be laboratories for federal policy, in this case, I really think before Scott Brown supports policies like Christie's, he should look at the results.

If you look at NY, also run by a Democratic governor, the results look like MA's. What is clear is that the cuts that Christie forced through have hurt the state of NJ