Double is at it's best when the Narumi Detective Office is solving problems around the city of Futo. Monster of the week really works for the premise if you're into that. The writers have captured the feel of a small town really well using reccuring characters and a fun, and memorable supporting cast. Despite saying that, the latter half of the series' more serious plot is arguably the weakest part of the show in my opinion. Regardless the series remains good throughout it's run, I was sad to be leaving Futo when it was all over.
Give it a try if you like the sound of that, or if you just think Double's suit is cool. You won't be dissapointed.