We stayed for 2 night in Impala Hotel, during and after our 8 day safari tour.
The rooms are average, the hotel is pretty old. On our second day in Impala we had problems with a non-flushing toilet. I complained with the manager, they upgraded us to executive room which was bigger.
I am not sure if there is much better choice in Arusha. Most of the 3* or 4* hotels in Kenya / Tanzania are very expensive and offer poor quality, especially if you compare them to hotels in Asia / America/ Europe. The reguler last minute price at reception is ± 90$, but our travel agents was able to get it for 75$.
The hotel is a 10 minutes walk to the center, but lots of people come after you if you walk on the streets. This guy kept chasing us because he thought he deserved a tip since he was talking to us, while we were just trying to be friendly.... You better get a taxi at night if you want to go to the center (2000 TSH), we heard there are some roberies in Arusha center at night.More