don't stay at the arusha backpackers. for all the claims that it is clean and cheap there are cleaner and cheaper options in arusha.
as for being remotely comfortable (or adequate) for $25 a night it is neither. we stayed in a bedroom that looked out onto an open corridor (the main corridor on the second floor) which in turn was open to the sounds of a petrol station refuelling and tinkering with buses (usually with their engines running) all night long. added to which they had the decency to turn on a generator around 9 o'clock in the evening to run all night, so if you couldn't sleep you could turn on a light to read.
the room itself was a double bed skirted by one foot of space on one side, the wall on the other, and room to open a door. the sheets were printed with the blazon of a different hotel and were clean in a tired and unshaven way that made them look grubby. the mosquito nets were full of holes (that is holes big enough for mosquitoes to fly through) and the showers were okay, but communal and nothing to write home about.
we barely slept and not for the right reasons.
breakfast was terrible. untoasted bread with crap jam, horrid butter, inedible eggs and lukewarm service.
some of the staff made a decent effort, particularly the manager, and she was happy to put valuables into a safe.
it was not good value, nor worth the money and we didn't sleep well or stay for more than one night.
if you are looking for a good hotel in arusha try the flamingo, it is equally central as the backpackers (ie the same cost in a taxi at night) and costs less than the backpackers does (Tsh 25000 as opposed to nearly Tsh 30000). the rooms are clean with en suite bathrooms. It is quiet (though near a mosque) and the linen is appealingly white. the staff are very friendly and capable and the breakfast is pretty impressive by comparison. you will probably need to book 24 hours or so in advance.
can't recommmend the flamingo over the backpackers enough.