Evidently YMMV, though obviously expectations play a role too, as I just had my first (one night) stay at the Churchill - contrary to some of the negative reviews I was very impressed.
My (u/g to club floor) room was ready for a noon check-in, and handled very smoothly and efficiently at the front desk when I turned down the offer to C/I on the 8th floor. Club lounge staff were super - warm, helpful and efficient. Yes, at breakfast, the 'one sided' lounge did get busy and crowded later in the morning, but the staff did a decent job of keeping things moving.

I had an issue with the room heating (the system would only cool), and the Eng staff showed up quickly, was also friendly, and had it all fixed in no time.
I did receive a lovely welcome note, big bowl of fruit, box of chocolates and half-bottle of wine.
My only 'complaint' is that the fitness centre is small and cramped, but Hyde Park is right next door...
For OsakaWino - I'd spent the previous night at the Hilton Park Lane, and although the hotel was fine, the lounge was also crowded, and the service was disorganized and frazzled. I felt like I spent a LOT of time waiting in line, and I was MUCH happier at the Churchill, as was my husband.
Enjoy your trip, whatever you choose!

How did you get from the Hilton to the Hyatt? Did you walk or take a taxi? I have some Hilton points that I need to burn and was thinking about spending a few nights at the Hilton before moving to the Churchill, buit did not know best way to get between hotels (and if the taxi may refuse the trip).

I agree that the Churchill overall is a better experieince than the Hilton, and more up to date in terms of hard product.

Its an easy walk between the two properties, if you have a lot of luggage, then a cab is an option.

Yes, I walked (with a roller bag) - directly up S Audley St, and it took maybe 10 min or so.

I have walked between the Hilton on Park Lane and the Churchill many times. It is fast and easy!

Plug adaptors
 

Is it safe to assume that the hotel will have plug adaptors?

If I remember right there’s even a standard US 110V plug in the room. I’m sure borrowing an adapter if you need one wouldn't be a problem, but make sure your equipment can handle 220V if you intend to use a borrowed adapter since most loaner adapters I have seen are just prong adapters and do not also function as voltage converters.

In the room we just checked out of - they have a 110V american plug by the desk in the living room - it was a suite, but I'm assuming that would be consistent to the other rooms. The bathroom didnt have a 110V plug.

Thanks. Just need to keep my laptop charged and then charge my shaver and camera battery once during the week. All 3 are 100-240 V.

I have never had any difficulty charging the small devices that you listed in the "shaver only" outlet that seems to be standard in most chain properties outside the USA. The laptop is the only one that requires a real outlet. If your room doesn't have a US compatible plug then I am certain you can get an adaptor from housekeeping or the front desk. Heck, most of them have a nice supply of charger plugs and cords, too, that have been left behind.

I'm writing this from a room on the Regency Club floor right now and here is what the power strip looks like by the desk:

http://imageshack.us/a/img818/6517/churchillh.jpg

It's a shiny chrome color so a little hard to see, but there is a single 110V outlet plus 2 different varieties of 230V outlets.

On a side note, having an excellent stay here. Regency club is even better than I remember it from my last stay 8 years ago (several hot items at breakfast now) and service has been excellent across the board. Checked in fairly early (1pm) and was told they wanted to upgrade me to a suite but the suite wasn't ready yet. They gave me the choice of a second suite on the smoking floor or a standard regency club room, and I chose the latter since I can't stand smoking rooms.

Thanks. And it is nice to hear that the club lounge is doing good. There were quite a few recent complaints about only one of the rooms being open. Hopefully that was only up through March when they were less busy. We're checking in next Friday for a 9-night stay and really looking forward to the lounge.

Just returned from four nights here.
I arrived early (6am) and was given a room to use for the day until a Club room became available which was very nice and appreciated.
The Club was good but as others have mentioned one of the Club rooms never seemed to be opened. Breakfast was good. Only managed to get to the Club for an evening drink once.
Amazed at how people on the floor I was on seemed to use the corridor as a 'meeting room'. They kept towels on the door to keep their rooms open and seemed to go from room to room, stopping to 'chat' loudly outside everyone's door.
Really loved the position of this hotel.
Really appreciated being given a 6pm checkout.
Just thought the rooms seemed a little dated and ordinary.
Oh, and the internet was AWFUL!

We are here now on the 3rd day of a 9-night. Both lounges are open for breakfast but only one in the evening. Have to say that the evening lounge last night was one of the worst I have ever experienced. Arrived at 6:30 and not a single place to sit. No wine glasses, no napkins. Incredibly poor food offerings. Some low-quality smoked salmon (much too salty), cheese, and chips. Very cheap wine. Places to sit opened up at around 7 and most of the food ran out. Rather than replace anything, they microwaved some frozen spring roles and passed them around.

Breakfast was exponentially better than the evening, but nothing to really boast about. Off to breakfast now; maybe try the other side.

Unfortunately not. I was there just over a week ago and half the lounge was closed again.