I had a beautiful Flemmie boy named Teeny (named after the wonderful Tiny), and he was so amazing. He was gorgeous, truly unique, and a card and a half!!
I would say...they're an amazing breed, most of them being really relaxed and fun bunnies...with the one drawback being that they typically don't live as long as other breeds. From the research I've done and the people I've talked to, you'd be looking at about five years. Their hearts are sensitive (both literal, physical hearts, and metaphoric hearts), so be aware that not only are they physically sensitive, but mentally as well. They need an incredibly stable environment (they don't respond well to changes or moving), and if you ever get mad at them, they take it hard because they're just really sensitive. They're very "human" bunnies.
BUT...the time you have with them is truly wonderful. I only had Teeny for less than a year, and he'd barely (as in, about a week) turned one year of age when he passed, but that's early for most. (I think Teeny had been a product of bad breeding, personally.) I am so thankful I brought that big ol' boy home. He was a really amazing bun, and such a great friend to have. He cuddled like no one else, and loved with his whole heart...and those eyes had so much to say!
Though I miss him like mad (lost him 10 Nov), I wouldn't trade that time I had with him for anything, and I don't regret one moment of it!!
So, while the time may be short...that time is really treasured and WORTH IT. I would recommend a Flemish Giant ANY DAY.
Here are a couple pictures of my baby boy:
And who could forget Super Teeny??