We really like the Netgear ReadyNAS products for performance and value (yes, you can spend more and get more, but most we work with have tight budgets). (Use enterprise class SATA drives)
Have never used anything we would consider "bad".
ReadyNAS has a great support forum which has always served us well; some VERY sharp people hang out there.
I really like them because they have redundant power supplies that we can plug into separate power SOURCES (different UPS feeds so we can do UPS maintenance or in case of UPS failure).
You can take a look at the ReadyNAS 3200 & ReadyNAS 4200 here:
http://networkstoragetips.com/netgear-readynas-pro-business-edition-review/
Best,
Roger.