The hotel has very small rooms but they are comfortable and very well-organized. The bath is also small but so useful. The hotel has a small garden and a fine dining room. Wifi was cheap (2 € for 2 hours and 10€ for entire stay).

The staff was very helpful, friendly and kind. I needed to work at midnight and they kindly opened the garden for me.

I would say it's:
good value,
good-sized rooms,
clean
comfortable firm mattress
good service.

Two suggestions:
Make wi-fi inclusive of room cost.
Offer a double duvet.

We stumbled across a couple of really good inexpensive restaurants in the local area (<5 minutes walk).

I have stayed in Hotel Aigner twice now, and both times I feel this is a great place. The staff is very helpful here, and the receptionist speaks in English. My german is very poor, and I can barely say a few basic sentences. In such cases, it is indeed helpful that the staff is understanding, and quite friendly and helpful.

When I reported that the cofee machine in my room was not working, the staff immediately had it replaced. They also have a hi speed Wi Fi network, which I use to chat with family and check mails. It is a bit pricey though, still I like the homliness of this place.

Mornings, from 6:45 AM breakfast is served, which is pretty good. Comes with Eggs, Bread, Meat, and Cornflakes. Some Fruit, and cofee/tea is included.

Rooms are cleaned daily, and the room comes with a mini bar. We can get our own beer, and keep in the bar if we so wish.

Overall an excellent place for the budget business traveller.

This hotel was ok for an overnight stay on route to another destination. It felt like a travel lodge, no atmosphere, servicable, reception staff were miserable. The position was ok for the paedestrianised areas of Bonn. Book a parking place in advance if you have a car.
Bonn was not sure what it was for me, there is a huge mix of new and old, not matched very well. The town planners do not seem to have put much thought into rebuilding the city after the war. The emphasis is heavily based around the classical music scene although the theatre is hideous!
It was an expensive city and you would really need to plan what you wanted to see before you got there otherwise you could wander around a miss the gems of the town quite easily.