You can't beat the location of this cute spot! The hosts were generous enough to let me rent the place for an entire month, were super accommodating and responsive, and dealt with the very few issues that came up swiftly and comprehensively.
The wine bar below is such a fun place to hang out, meet people, and see incredible local music. I especially recommend the Tuesday night band--they put on one of the best musical performances I've seen while I was there, and even invited my brother's girlfriend to sit in with them on trumpet. It was a night we'll never forget.
The street noise really wasn't a problem for me--though there is definitely some noise. I'm used to a super quiet room and I made it through just fine. A white noise machine would take care of most of it if you're sensitive to noise. And, the bar downstairs quieted down pretty early. I wouldn't let the street noise deter you whatsoever if you're considering staying here.
For folks who are super sensitive to environmental allergens, I think this unit might be a bit of a risk for you. However, unless you are staying a long time or are extremely sensitive, it likely wouldn't pose a problem.
I loved my stay at 5 Walnut and would definitely stay again and recommend it to others!