Not only are the new features really useless (like the 401k and paycheck crap that we could already do) but you actually lose features if you don't upgrade to the deluxe version.
On my system, the upgrade even runs much slower.
(There is one bright spot for those that use Home Inv. In the past changing an item changed the entire history. Now it only changes the current period. However, this isn't so much a feature as it is a bug fix).