I came to this hotel after another hotel in Oslo sent me here when they made a mistake in their reservation system and sold me a room that they did not have available (long story, but we were about 7 people in this same predicament).
At first I was apprehensive as I needed to be in south Oslo and Lillestrom is to the northeast, but I had a pleasant surprise when I made it here. The train station is across the road and from there I was able to take the intercity train to central Oslo for just a few Euro / NOK. From this station I could also go to the airport, so location-wise it was very good.
The hotel itself caters more to convention-goers as the convention centre is next door. Nevertheless the staff were very friendly and were helpful in arranging a room for me in the very early morning.
The room was nice. Comfortable beds and clean bathroom area. The TV had many choices for English language stations, which is nice for those who do not speak Norwegian.
Breakfast was served in the main restaurant and was very good. Wide selection of cold cuts and some warm dishes, therefore something for everyone's tastes. For those not wanting to eat in the hotel, there are some small restaurants across the road between the hotel and the train station, which appeared to be quite popular. In the station itself there are small outlets where you can also get snacks and drinks should you not want to have a large / heavy meal (also lighter on the wallet!)
So for a nice alternative to Oslo, you may want to consider this hotel if the price is right!

A bit surprised to see the latest reviews. Have used this hotel a couple of times due to lack of rooms in Oslo - and due to the hotel.

a) Non-stop trains run every 10-12 min. during rush hour. They will bring you directly to Oslo in 20 min (incl. a 6-8 minute walk from the hotel). Buy a ticket at the station or use one of the carriages with blue doors (they have conductors selling tickets for a surcharge of 20 NOK)

b) Rooms have air-con and heat-regulation - on the wall next to the bathroom door.

c) Rooms are spacious, the air is clean, wireless is free and reliable, and service is the best I have experienced in Norway.

Best of all - the breakfast is outstanding. Fresh orange juice, omelets made-to-order, a scenic view, and waiters making sure the place is kept tidy.

we were a delegation of six looking for a hotel to stay in during the CW23, for various reasons the hotels in Olso's city center were already fully booked so we were put into the Thon Hotel.
The good things first:
+) it is conveniently close to the Lillestrom train station, a direct train goes every 20 min or so and will take you to Oslo S in 11min for 60NOK (approx 10 USD) one way (tip: by your tickets at the various ticket machines, some trains run without conductor and then the penalties are fierce, also on the train your will have to pay 20NOK premium).
+) there's a steakhouse and an Indian restaurant just 50m away from the hotel if you don't like the hotel's food
Now to the rest:
-) my room was a double bed room, meaning they had put 2x 70cm beds next to each other.. the cover looked like it had been washed a million times already and had a nice big cut in the middle.. the linens for the duvet were at least 50cm too long - why would one do that?
-) Wallpaper looked a bit bloated from what I suspect water damage but no visible mold anywhere.
-) No safe box in the room - hate that, would love to store documents and expensive hardware during the day..
-) The smoking room smelled like it had been smoking itself.. obviously the A/C did not handle the smoke nor did they apply any air freshener when cleaning.. gross.
-) my colleague arrived later and despite having a confirmed booking was asked to wait around midnight after check-in because the only room available had a water piping problem which required fixing..
-) one of the evening we arrived at 10:15pm and were hoping for a quick dinner at the hotel restaurant - after 15min waiting outside we were informed that the kitchen was closed and we could only get hamburgers.. fine, actually quite a good bite but the waiters, aching to go home, were a disgrace, doing the best to avoid taking any futher orders for drinks. finally we were complimented out of the restaurant.
all in all it wasn't a good stay, not for a hotel that claims to offer 4* service.

Well if this hotel is number 1 in Lillestrom, God help the rest!

A catalogue of errors by this hotel means it gets a 1/5.

1. A lengthy check-in queue being handled by 2 staff. I had to make my first complaint within 5 minutes of entering the hotel.
2. The hotel room was extremely warm - opening the window was the only option as there is no air conditioning or temperature control. This makes the room noisy. I had a totally sleepless first night.
3. I had a parcel waiting for me on arrival and the check-in staff asked me if I could take it up to the room. As I was with a case and a laptop pc (there are no staff to help you with your luggage!) I asked if they would mind bringing it up to me later. They looked at me like I had asked something quite out of the ordinary. They agreed and then proceeded to leave the parcel down in reception until I had to go down myself and pick it up the next day.
4. There is a mini-bar but not stocked well and all the drinks were warm.
5. The room service on offer is an agreement with a local pizza delivery company!!

These are just five of the problems I experienced. The staff (with the exception of the member of staff who brought a bottle of orange juice to my room!) were useless and clearly do not understand the meaning of customer service.

I would not recommend this hotel at all.