Yes, it's not perfect, but I suppose it's a 'get what you pay for' thing. I don't know about Mint, but with Linux Mandriva 2009 you can get a paid-for codec instead of libdvdcss and I would hope that would entail a picture as good as when I watch a DVD in my Vista partition, which to be fair is still not perfect either, probably down to a not great graphics chip in my laptop, a factor which may be involved in your situation to, eh. I wouldn't know if Mint can use a better, paid-for codec.
You notice the choppiness most with sideways motion, don't you? Picture kind of moves in strips. Let's hope the programmers evolve this.