I do not own one now, but have owned two different ones in the past. I know one of them was a Kenmore and never had any real problems with it. I think you need to look at where you have to put it and then determine how much hose you need to reach the faucet.
I know that in one apartment I was able to put the dishwasher at the end of the counter the sink was in and the hose needed to reach to the sink.
Other features I would look for in it are the same ones you would look for in a regular dishwasher. Look at the cycle settings and see what is important to you. Some might want a miser setting and others the pots and pan setting. Also look to see if you are able to put large items in it. The top shelf having an adjustable height is also nice.
we had one in an apartment before we bought our house. it actually worked better than the built in one we have now. i don't remember the brand, but we loved it and it had a butcher block top that we could actually utilize as space. the only sucky thing was we had to wheel it right over to the sink to use so that area was off limits while it was running. oh, and obviously you can't use the sink to wash anything since it is connected. i am guessing this post was totally not helpful at all:)
