London Marylebone Train Station is situated in Marylebone (I know, who's have guessed!) in Central London.
Marylebone station is one of the smallest mainline stations and has just 6 platforms, compared to Euston which currently has 18. I find the smaller size of Marylebone station is a bonus - with fewer platforms there are fewer trains coming in and so fewer passengers.
London Marylebone station is served by Chiltern Railways (who also manage the station) and Wrexham & Shropshire trains. So trains go to & from North East Wales, Shropshire, the West Midlands and the counties North East of London (such as Oxfordshire and Buckinghamshire). This means that the Chiltern trains (and Wrexham & Shropshire trains, on special occasions) stop at the Wembley Stadium station which is usefully situated right next to Wembley Stadium and a short distance from Wembley Arena. I would recommend using one of these train services to Wembley Stadium as I find them a lot quicker than catching a tube train on the Underground.
Marylebone station is situated halfway between the mainline stations of Euston and Paddington and just a short walk away from Baker Street tube station, although Marylebone does have its own underground station beneath the mainline station. Nearby hotels include the upmarket "The Landmark" opposite the station and the more down to earth Marylebone Travelodge just a few steps away. This being central London - shops and pubs are nearby too.
Inside the station, you'll find shops such as WH Smith (handy for some reading material, whether it's a novel or just the daily newspaper), a florist (which looked to be still open when I passed it at 11.30pm one evening!), Marks and Spencer's "Simply Food" (my favourite place to go to grab some food to take on the train), a card shop, Burger King, a soup seller, a sandwich shop, a pub and others.
Facilities such as phones, cash machines and toilets are also available. There is bike storage too (on a platform), but I believe you need to have a season ticket to use it. Seating is also available (useful when you've got a heavy bag and a bit of a wait until your train comes in).
The platforms have ticket gates, so you'll need a ticket to access the platforms. I have found that staff are usually on hand when trains are arriving and departing, and I've found them to be friendly and helpful.
I find Marylebone to be a clean and tidy station, and unimposing. Due to it being one of the smaller mainline stations, I don't find it as busy and as crowded as the other stations. I rarely struggle to find a seat (if there isn't a free one, it's usually not too long before one comes available), where as in a station such as Euston I usually have to settle for standing, leaning against something or sitting on the floor.
As I mentioned earlier, Marylebone station also includes a tube station. The ticket office for the tube station is situated inside Marylebone mainline station, right by the tube station entrance. The tube station is on the Bakerloo line in Zone 1, However, Baker Street tube station is a short ride (or walk) away and it lies on 5 different lines - Circle, Hammersmith & City, Metropolitan, Bakerloo and Jubilee.
I used to catch the train from Mid Wales & Shropshire down to London Euston station, but now I prefer to travel with Wrexham & Shropshire Trains down to London Marylebone. I find Marylebone station more pleasant, staff are easier to find and talk to, and in general the station isn't as imposing as London's larger mainline station.