I bought two copies (for co-op with the wife) from Amazon at a similar price months ago. In the end, it was probably about as enjoyable as the first one. I bought the premium DLC when it was on sale (which it might currently be on sale).
The game pretty much plays the same, minus the strategery between eliminating certain gang leaders first. During the day, you're main enemy are the Cell, at night, the Freaks come out and attack everyone. The most strategy you'll use is attacking the Freak hives at night, while they're out on the streets.
The Toy Box pack provides some awesome extras, such as a helicopter you can call in, and "suit thrusters," which are essentially jet boots to get you an extra bit of height/air time to get around -- especially useful in finding/getting orbs. Plus (I believe) the 3 agent cars from the first game, in their souped-out forms, and some other vehicles/weapons.
I've never played it solo, so I can't speak for it, except that its [obviously] the same, just without a partner/backup (which makes it less fun IMO)
Easily worth a pickup (or two for co-op) at this price (IMO), especially if the DLC is on sale.