Stayed for 2 nights in late October 2009. The hotel is enormous and, being part of a chain, you know exactly what to expect. The public areas are fine if bland, the rooms comfortable if slightly cramped, the location good for tube and bus but just a little 'distant'.
Check-in was pain-free but limited - there was no mention of breakfast times, room departure times nor (most importantly) how to operate the lifts. This was with your room card ( and is a very good idea ) but some instruction would have been useful.
The hotel was clean throughout, the breakfasts ( Continental and British) were good and wholesome.
Overall, fair value for money - basically just what we expected. Is it fair to expect just a little bit more?

This hotel is only a 1-minute walk to the Gloucester (pronounced Glahster) Road Underground station (called the Tube). Even though the address states Cromwell Road, the hotel entrance is actually facing Courtfield Road. I went to the Holiday Inn around the corner on Cromwell Road and it was the wrong one. So, from Heathrow take the Tube to Gloucester Road, walk up the stairs, turn right at the ground level, turn right on Courtfield, walk 1 minute and the hotel is on the right.

Walk out of the lobby of the hotel, turn left on Courtfield Road and you'll hit Gloucester Road about 1 minute later. There is a KFC (Kentucky Fried Chicken), Pret a Manger, and a Tesco Express right there on Gloucester Road. There are also a few pubs and some nicer restaurants but they're expensive, at least for Americans. The Tesco Express is good because you can grab ready-made sandwiches, chips (called crisps in the UK), pastries, cookies (called biscuits in the UK), etc, which is perfect for taking lunch or breakfast on the go. I went to Tesco in the morning to buy a croissant or pastry, then took it back to the room to eat it with freshly brewed tea. The rooms have an electric tea kettle and the tea and cream is provided.

The Holiday Inn Kensington Forum is fine if you like large, impersonal hotels with mediocre service, overcrowded breakfast rooms and don't mind tired decor.
We use the Holiday Inn brand a lot and trust it. This is the first time we have stayed at the Kensington Forum and is probably the last, unless we get an incredibly good deal.
We found the front desk service unfriendly and indifferent. The hotel was very busy on the night we stayed and queues at the lifts were a little tiresome at times. The room was clean but tired as were the public areas that we saw. The bedroom, although recently upgraded with a new bed (very comfortable) had wall paper that was unstuck at the seams throughout the room and the rest of the furniture appeared the quality of a budget hotel brand - the TV was an outdated model. The room was quiet apart from the hum of the minibar. Breakfast felt hassled. The room was packed to capacity with queues at the food buffets. The over zealous (but attentive under the circumstances) staff cleared our unfinished drinks while we were collecting cooked food and movement around the room with plates was difficult in the crowded circumstances. The location is excellent - near to the Tube and walking distance of a lot of attractions.
I think we could do better next time however.

Used Hotwire for the first time, requesting a 4-star hotel in the Kensington-Chelsea area. Turned out to be this excellent property in a prime location. Half expected a noisy room by the elevator for the bargain price we paid, but instead got a 17th floor room with awesome city view. Location could not have been better with the Gloucester Road tube station just a few minutes' walk from the hotel. Piccadilly and Circle lines took us everywhere we wanted to go quickly and conveniently. Excellent grocery store on the corner made it easy to keep our in-room fridge stocked with breakfast items. Concierge desk staffed by knowledgeable and friendly gents whose recommendations were consistently excellent. Room was comfortable, very well lighted, and well maintained by housekeeping staff. Only negative was that the room, fitted with twin beds, was small even for just two adults. Also, I suggest taking your own wash cloths, as they were removed daily but not always replaced. Bottom line is that I would definitely return to this property for its comfort and convenient location.