I also like its modularity. We've seen different versions of the Miranda on TNG - with and without the rollbar, some with sensor pods, and such. It seems that by the 24th century, a good chunk of the Mirandas were being used in secondary roles as transports and cargo ships. Not surprising, given their age.
Their age also worked against them during combat. I would actually cringe while watching the space battles on Deep Space Nine, anytime a Miranda charged into the fray. As tough as they were in the 23rd century, they weren't up to snuff in the 24th. It was like watching a senior citizen take a roundhouse kick from Chuck Norris.
Still, I would jump at the chance to sit in the captain's chair of one back during its heyday. Just not the Reliant, because I know how that shit goes down.