This does exactly what it advertises - provides basic accommodation in an amazing location. So if your surroundings is more important to you than your bedroom then stay here! It's about a minute's walk from the Pantheon and has one of the best coffee places in Rome almost next-door (Sant'Eustachio). It's on a gorgeous cobbled narrow street and the sounds of bustling Italian life going on below in the morning is a joy.
The rooms are clean. Breakfast is provided, though it won't be one of the highlights of your stay.
NB. The building is on the opposite side of the street to where it's number is displayed! Look for the little intercom where it's written. If you have any trouble as the policeman who sits in a box nearby 24/7!!

My wife and I stayed here for four nights-five days in Room-B (Aug 9-13, 2011), which had an attached bath.
Plus points:
1) 50 yards from Pantheon and within 15-20 min walking distance of most major sites.
2) Very inexpensive hotel considering the fantastic location. Don't expect the moon for 95 Euros a day.
3) Plenty of eating places of all kinds (two of the best gellaterias in the area)
4) Quiet, given the location
5) Friendly and helpful staff who speak several languages, including English. Front desk open round the clock (one man insisted that we have breakfast when we checked out at 7 a.m. on the 13th even though breakfast officially starts at 8. He also made us fresh Italian-style coffee since we were coffee connoisseurs). Breakfast laid out includes rolls, croissants, biscotti, butter, jam, meusli, cornflakes, milk, coffee, tea, hot water, orange juice.
6) Recently renovated (???) since toilet fixtures were new in our room.
7) Clean sheets and towels (towels were replaced on second day), soap and shampoo packs daily.
Minus:
1) Our room barely had a view -- of a crummy wall opposite. But then, we came there only to sleep at night. Double bed, one extra bed/couch/diwan whatever. So, can sleep three.
2) Shower temperature erratic. One minute it's icy cold, the next minute, it's scalding. Front desk man promptly leaped up to fix it when we pointed it out. Problem continued for the next three days. Sigh.
3) Mimosa accepts only cash even though the website gives the impression that you can pay by credit card. Computer printout on front desk claimed -- and I use this word deliberately -- that they were having problems with the connections and that credit card is only for making reservations. But I'm told by a resident of Rome that a cash-only policy is quite common in pensiones, probably as a tax evasion ploy. Confirm before you make a booking if you cannot pay cash. Cash machines are plentiful near the hotel. Watch out for 19.5 percent commission at cash exchanges though (listed in small print at the bottom of the exchange rates).

You might have a problem finding the hotel. It's a dark green door, with a 1ft x 6in metal plate sign just above the listing of all the building's occupants. When facing the Pantheon, walk to the back on the right side of Pantheon, on via della rotunda. go about 25 yards after the pantheon building complex ends.Then turn right on via di santa chiara. It's the second or third green door on the left. The sign is almost invisible. Almost opposite it is a small coffee and sandwich shop that opens usually around 6 a.m. and serves coffee from 7ish. Overall, I'd recommend this for couples.

When your 100 meters from the Pantheon and only paying 90 euro a night, you know you’re not getting a 5 star hotel here. It is a 1 star hotel after all. We stayed there for 6 nights. The staff was friendly, nice and very helpful. Had a double room with private bathroom. The room was decent. Full size bed and an extra twin, a wardrobe for our clothes and a nice size bathroom. Breakfast was typical - cereal, croissants, rolls, coffee & juice. We wished there would have been a refrigerator in the room but they did have a small selection of cold drinks in the lobby. It is a GREAT location. Right in the middle of everything. Very convenient to a main road, so very easy to catch a bus anywhere all over the city. We even got a 10% discount on our room because we had a Frommer's travel guide.

Really I don't know what some people who write these reviews expect when they're paying 90 Euros to stay right in the centre of Rome! Yes it's basic, but I found it to be clean and the staff helpful. The air-con is a real plus too if you're planning a visit in the middle of summer. The location is truly hard to beat. I would go there again.