Went to Frankfurt without hotel reservation, found there were many lodgings around the main central station. I walked into this one and asked for the price for one night, because I was attracted by its modern and clean entrance decor, in stark contrast to most other hotels on the same street. They paid as much attention to the rooms as its front decor. When I finished "researching" and went back to book a single room for two nights instead of one, they automatically deducted 10euros/night from the original quote they gave me.
The room was very clean, as was the bathroom. I thought the room was spacious for European standards, which had two single beds pushed up together. There was a mini fridge in the room, and no air-conditioning, but a standing fan. Everything looked fresh, modern, and clean, and everything worked. There is a grocery store right across the street. The area is a little shady, but so is the larger area immediately adjacent to the main station.
The staff were polite and professional. You could tell this hotel was run by some very responsible owners. It was more than I expected. The wonderful price was just a bonus.

The location of this hotel was ideal for my purposes - right in the centre of it all! It's just a couple of minutes walk from the Hauptbanhof (central train station) and it couldn't be any easier to find - Munchener Strasse is well signposted and there's even a pedestrian underground walkway from the station right onto the street.

Don't expect luxury here - but it's certainly clean, comfortable and perfect if you just need somewhere to rest your head. I had a few great nights sleep here - the pillows are nice and firm (which was a nice surprise, as I usually find hotel pillows too soft) and the bed comfortable. The walls are a bit thin, so you do sometimes hear noise from other rooms - and I was only on the first floor so I could often hear people in the foyer downstairs too - but it's not a dealbreaker as the noise was never a serious issue.

The only other slight negative is that the shower left a bit to be desired - there was no proper 'stand' for the shower head, it was just hanging loose from a hook on the wall, so you have to hold it in your hand all the time - but apart from that it's fine, as the water pressure was nice and strong.

Service was understated, polite and efficient. Don't expect big cheesy grins, or for them to be over-friendly, but then that's not the German way - do expect them to be pleasant and keen to help though. I stupidly managed to lock my passport in my room's safe by accident within minutes of arriving (don't ask me how!) The man at the main desk was patient, helpful and reunited me with my imprisoned passport within minutes - a bit of an embarrassing incident on my part though!

Breakfast is provided, although I never surfaced early enough to sample it (preferring instead to pick up Bratwurst from a nearby fast food joint) and there is a free internet terminal just past the main reception desk which is handy if you need to quickly check your email or whatever.

If you're heading to Frankfurt, and don't want to spend too much on a room, then then the Munchener Hof is worth a look. I'll certainly be staying there again whenever I next visit the city.