For day to day use it is fine. I only know the mini is on because I can see the power light is on. The DroboPro makes more noise although that is only when the fans kick in, otherwise even when right next to the system it is silent. I get more noise from my MBPro keyboard when typing on it.
For web browsing and word processing etc then the box is fine and extremely power efficient. For video playback then the 9400m chipset is great and more then capable of playback of HD/1080p material. The mini comes with a mini-dp and also a mini-dvi to dvi cable so you can connect to a normal non-Apple monitor or get a DVI to HDMI cable and attach to a HDTV if you want.
I use the ElgatoTV with a Turbo264HD encoder for TV Recording on mini and encoding into iTunes, along with an AppleTV in the bedroom which I share the iTunes Library too and playback on that is fine, when streaming from the mini.
Even when recording or exporting into iTunes then the box works fine.
As a media pc / general purpose machine then the mini is a great box but it is expensive on paper specs for what you get, and unless going down the OSX route probably not worth the extra money, unless the space is really critical.
For DVD Ripping I personally find the mini too slow but that is what the Gigabyte/EFI-X system is for