Pluses (compared with the 2000 series):
1. Four channel vs. two channels for 2000 series (currently)
2?. Hopefully standard RS232/SPI/I2C triggering and decode? It doesn't really specify, though it's somewhat doubtful since I can't think of many scopes with standard decode. Triggers are standard for 2000 series, decode is optional
Downsides:
1. 12 Mpts standard, 24 Mpts optional for 1000z series vs. 14 MPnts standard, 56 Mpts optional 2000 series
2. 30k wfms/s vs. 50k wfms/s
3. 1 GSPS vs. 2 GSPS (I'm guessing 1000Z might have 2 ADC's with 1/2 coupled and 3/4 coupled, though even this is slightly disappointing)
4. 7 inch screen vs. 8 inch screen
5. Lower vertical resolution (2mV min vs. 500uV min)
6. Lower max bandwidth models available (no 200 MHz version for 1000z)
Everything else seems like the 1000z takes a lot of form factor from the 2000 series, might have a few other differences.
I suppose it would be useful if you really needed a 4-channel scope for fairly cheap (100 MHz 1004z scope ~$1000 USD claimed, 100 MHz 2102 scope is listed at ~$1100 USD). Other than that, I'm not sure I would go for it over a 2000 series scope.