All in all, Miranda is unlike other British sitcoms because it's about something other than people with stuffy accents bickering with each other.
"Unique" doesn't exactly mean good, however. While it's watchable, pretty damn funny at times, not to mention the fact that Miranda is Adorkable
incarnate, and all in all with its own style, it's nothing particularly special, though I still suggest you watch it simply to see if it's for you.
For me, the humour is a bit hit and miss, though it's usually on target.
All in all, a funny series with nice characters. If that's what you're looking for, step on forward. If you want something with a little more depth or high-brow-ness
, then move along. The show at least know's who it's targeting, and does that spectacularly.