SoccerMum, just seen this thread and thought I'd add my pennies worth
I've recently been in your position, but it was about getting a cat - I really wanted it, but dh didn't, although he loves cats. It was the responsibility and the long term commitment, although as we already have two dogs my point was that it wouldn't make much difference. I KNEW he'd love the kitten when we got her (I was pretty much adamant that we would) and although we had quite a few arguments about it and had a couple of days hardly speaking, I went ahead and brought her home...
Three weeks later and DH is smitten! They spend every evening snuggled up on the sofa together and he loves playing with her, but as expected it's me who does the looking after, which is fine.
What I'm trying to say is that it depends on how well you know your dh, and whether you think he'd come round to the idea if you bought a puppy home. My dh is a stubborn so and so, and I was 100% sure I was doing the right thing for both of us, even though he couldn't see that at the time
Kittens are a lot easier than puppies, and tbh I don't think I would've done the same with a puppy as they are so much more a member of the family iykwim? DH was on board before we got both of our pups, and it was hard work at the beginning so it took both of us to handle it...
There are arguments for and against what you're thinking of doing, but only you know your dh, and if you really feel that it's the right thing to do, then maybe you should. You have to be sure though!
Good luck!