The hotel is a 3.5 on a 5 scale. The 2 rooms I stayed in while awaiting flights out of Heathrow during a 2 week, 4 country visit to Europe on business were spotless, surprisingly quiet, and quite comfortable. This is a basic hotel that lacks upscale amenities, but their low price (US$110) and excellent service made it a great bargin compared to the high priced hotels (US$250-$375) I also stayed at. I'll definately stay here again when I have to travel out of Heathrow.

The front desk staff were always very friendly and efficient regardless of how busy they were. Check-in / out were fast, and they cheerfully accomodated my request for a 'quiet room' on a higher floor.

My only complaint with the hotel is the high price for the hot breakfast. While the selection of foods was adequate, I chose to eat at Heathrow for about 1/2 the cost.

The hotel's location is very convenient to Heathrow. I took other traveller's advice and caught the red bus from Central Station, a 10 minute, free ride to the hotel. It stops about 100 feet from the hotel's front door. And if you're looking for great Indian food, catch the bus to Southall (20 minutes / L$2) and treat yourself to the Brilliant Restaurant without having to travel to downtown London.

Stayed here two night on a business trip. Very small room, with very small double bed (double room for single person booked) - if two had been sleeping in bed it would have been very uncomfortable.
Water pressure on third floor very weak.
Half a bottle of coke left in fridge by previous occupant, as was some of their hair in the bathroom :(
Breakfast good.
Viewed as purely an overnight hotel, if clean, hotel would be ok - anything longer - forget it - unless you get a premium room if there are two staying in same room.
I will try somewhere else next time....

I travel quite a bit for business and off stop off at Holiday Inn hotels around Heathrow. I have stayed at Ariel about 4 times but my last stay in August 2007 was unsatisfactory. The reception and room service is lousy. But it is a cheaper alternative so if you can deal with rude front desk people then the room is fine - just make sure to get a toilet that works well.

There are many hotels to choose from around Heathrow airport. The Holiday Inn Ariel is middle of the range in terms of pricing, and a very good choice. My room was very comfortable with a large bathroom (by European standards, that is). They have a small bar area and restaurant; the food was pretty good. Something I didn't know about Heathrow is that to get to the "airport hotels" you have to take a shuttle bus (called the Hotel Hoppa; 4 GBP each way). It ran pretty efficiently, just be sure to have the $$ on hand!
The only drawback is that the walls are quite thin and I had a very noisy group right next to my room.