I've stayed at the Thistle Euston several times over the years and it's always been a pleasant experience. It has often been used as a "bus tour" or group tour hotel, which is how I first stayed there. The location is very good, just a block from Euston train and underground station and around the corner, on Euston Road, is the Euston square and Warren Street stations with in a block or two. Euston station is a major bus terminal as well. I didn't notice much noise from the trains and the neighbourhood itself is quiet. It's close to Regent Park and Camden too.
The hotel has a nice little bar and a restaurant in the basement, both have pretty good food, though a bit pricey as you would expect from a hotel. If breakfast is included, when i was there at least, it was a continental breakfast served in your room. Between the first time i stayed, in 96 and the second in 2000 I think the hotel had refurbished. Certainly redecorated and it was much nicer.
The rooms were average sized, nicely decorated and air conditioned. Nice television, there was a desk and chair and some side chairs as well. There are lifts in the hotel but some of the hallways also have a short flight of stairs so check where your room is if you have heavy luggage or mobility problems.
Price is not budget but not too expensive either, though one year I booked it via londontown.com and got a ridiculously low price of 35 pounds per night. I've never seen that since and I think it may have been because it was over Easter weekend. They were willing to extend my trip for one extra night at the same rate as well, when i contacted them privately. I won't say the staff was overly friendly but they weren't rude either, just busy. I did get sick on my last stay there and they were helpful in contacting a doctor for me.
I'd reccomend this hotel for the location.