We really enjoyed our stay at the Denver Resident's Inn.
The only real issues we had were minor - the water wasn't fully filtered at first, it needed to run a few times to clean itself as it had some spots, and the coffee maker stopped working, so it had to be replaced, again though, very minor. Also, minor again, we were surprised parking was quite expensive - considering the lot was fairly empty.
As for positives - the location was really nice and convenient, the service was excellent - any time we needed anything, the response was quick, and the staff was very friendly (we thought the staff at breakfast was especially accommodating). We felt we had everything we needed for a week stay.