Pros Very easy to set up. Accessible from any OS. Some great features - in particular uPNP media server, simple Bit torrent downloads, drive synching that remembers your settings for each drive.
Cons Online support. Don't bother buying this unless you have someone you can grab by the scruff of the neck if things go wrong. Believe me, I bought online and regret it bitterly, always a case of 'not my problem' if you can get a response at all.
Summary I recently bought the 8GB ix4 unit and I have been trying to get the faulty drive it arrived with replaced for 3 weeks now. It would seem the unit does everything I wanted of it but having bought it online I can't get any response from Customer support. It isn't the quickest NAS I have ever used and with a faulty drive it keeps trying to rebuild the RAID 5 - which slows the unit to a crawl. Do NOT buy online unless you have endless patience or are willing to replace faulty drives out or your own pocket.