I have had this for a while now and I just find it so invaluable.
I back up my files to the NAS on a regular basis and also use it to stream my Music via the Itunes Server (which is great) and my movies.
I have not had any problems with this unit and I just find it a dream to use.
There are a number of downloads that can be used with it, but I would love there to be more.
There are 3 USB ports (1 on the front and 2 on the back)and 2 Ethernet ports on this unit, so plenty of connectivity for networking and adding a USB printer or external hard drive for backing up the NAS.
I have a UPS connected to mine as I had a couple of power outages and was afraid that the NAS would be damaged (the UPS is worth it given the cost of this unit)
I purchased my NAS driveless, but then added 4 x 1.5T hard drives (probably overkill)
I do find the fan gets rather noisy. However I you can go in to the settings and reset the Fan speed.
I did try to use the back up software that came with it, but for some reason it stopped working as it said it was a trial version. I could not find the product key to get it going again and never got round to sorting it out so I removed it.
However, I just bought Acronis True Image 11 to back up my files but have to yet set this up.
Overall it's just a great piece of kit that I don't know what I would do without.