We stayed here for three nights as part of a tour across Northern Germany using the public transport Deutschland Ticket, with Google Maps giving us directions and timings. Eilenriedestift have a big site 35/45 minutes out of the centre by bus and tram/rail, in a very pleasant and quiet area with supermarkets and bakers within 10 minutes walk.
The bed was really comfortable and the balcony had enough room to eat outside. We really enjoyed pottering in to Hannover and following the Red Thread on one day, and the Herrenhausen sights the next day, especially the big proper botanic garden where everything was labelled!
The staff were friendly and welcoming, though we really didn't need to approach them as everything we needed was provided. We met a very helpful Scot right at the end of the stay who has been there 25 years who will give good local recommendations - we did have an excellent meal at the local Croatian restaurant, and we could have eaten in the restaurant at the site but chose otherwise.
You must be prepared to walk to and from the site if you don't drive. We were, and Eilenriedestift suited us. We thoroughly enjoyed our stay.