I stayed for a one night before an early flight from Zurich Airport, and this seems to be exactly what the hotel is set up for. Check-in was quick, shuttle to airport frequent and bang on time, rooms clean, decent bed, decent bathroom, internet etc. Allegra seems to be very efficiently run. It not right next to the airport but is easy to get to, a few mins walk from the Kloten station.
So for a cheapish place near Zurich, or a short stay before a flight, I'd definately recommend it. That said, there is nothing exciting or charming about it; it's just a well run three star hotel.

I stayed here for business and have no complaints whatsoever, which is what good business hotels should make you say.
True, it may not be a proper four star hotel and the lounge and common areas are better than the actual rooms. I found the beds for instance not too comfortable but it seems to be a recurring issue in Switzerland (come on, get yourselves some decent orthopaedic mattresses!).
Breakfast was pretty good and so is the location and the shuttle service to and from the airport. Train stop is litterally behind the hotel.

This place was so cool, the rooms are huge, don't stay anywhere else. It's extremely close to the airport and easy to get to with the shuttle.

This is described as an airport hotel. It can be reached by taking the free shuttle from the airport, but it takes about 10 minutes journey to get there. The hotel check-in area is reasonably stylish and the staff were efficient and friendly. I was disappointed with the room. Very basic. The twin beds were advanced camp Beds. The mattresses squeaked badly with each move. The bedding was cheap looking. The room had a kettle for tea or coffee but the switch was faulty. There was a safe available, but the coding was complicated and the door locked when it was open and could not be reset. Most rooms have an umbrella available, but mine was missing.
Breakfast was uncomfortable: I was offered full breakfast or basic light breakfast. The basic light one was only tea/coffee/hot chocolate plus cereal, or bread/toast. The full one was as above plus meats, cheese, eggs. I elected for full and was ushered to the "full" side of the two breakfast eating areas. First problem was where to sit? There were 6 tables. One table for two people, two tables for four people, and three tables for six people. Each table had one person. I chose to sit at the opposite end of a six seater, with a stranger at the other end. It worked ok until his colleagues joined him! I understand enough German to know they were questioning who I was.
Overall, I will avoid this hotel next time.