I travelled from India, and this for my first stay. I am on a predoc position at Caltech, so I can tell about how commute to Pasadena is as well.
1. Arcadia is probably the safest place in the region. I left for work, and walked to the metro at around 5:30 AM, and never had any problems. The area is quiet, but has a lot of cool places nearby (almost everything within a mile).
2. The place is amazing, and feels extremely homely. The owner is very helpful, understanding and goes length to help you with every possible thing. They offer you everything that you will need (and a lot more).
3. Commute to Pasadena is smooth if you have a car. Public transport can get a bit on your nerve but even that can be figured out.
I would have loved to stay longer, but the place got booked for the following months. In conclusion, would heavily recommend for long stays.