I have both, and to me, unless you need wired ethernet and svideo, get the roku2. The adaptive streaming is great (people complain about the first 30secs looking like poo, but they have never had a glitch in the middle of a movie and your netflix stream downgrade and never come back up untill you pull the plug), you can have games, the box has more memory, and to me, is more responsive.
I know it has been glitchy, but Roku has been diligent in squashing those bugs, and to me there aren't many left. I have run out of memory on the roku1 and it is a drag to have to limit yourself. Plus, there might be channels in the future that ONLY run on the roku2. AND, you already have a roku1, so in a pinch, you can just use that one if something doesn't play in the meantime.