I'm planning a trip on the Trans-Siberian, and I've noticed a huge price difference between the Platskartny (3rd class bunks; $73 USD) vs Kupé (2nd class bunks; $241 USD)
I've seen some pictures (http://www.seat61.com/Russia2.htm), but i was hoping for some first-hand experience as to the differences between the two classes. I would love to save some money, just as long as the 3rd class isn't *really* bad
I can maybe help.
I travelled by rail in Ukraine last October from Kiev to Dnipropetrovs'k. It may be similar to Russia. We travelled 3rd class the wya there which was an open area with bunk compartments like no doors and people can walk by your bunk. We travelled 2nd class back and we got a Cabin with 4 bunks and a door with a lock.
Watch out for crazy people on the train coming into your cabin
Platskartny is fine.
I always use it wherever possible. As well as being cheaper it is often more sociable and fun as well. Platskartny is basically two rows of bunks, with another 2 flat against the side of the train, kind of making a 6bed partition, but with the open corridor passing through it.
If possible, you want to avoid the ones right at the end of each corridor (especially toilet end) simply as they are louder and more people pass by you.
If you go on to the TP Blog section (left) and search "platskartny" there are a number of entries that I have put up including some pics, which may help give you an idea, at least, of what you are in for. Also, gregw has a very good overiew of the trip http://gregwtravels.travellerspoint.com/9/ which may be of interest
I've done literally hundreds of train journeys in Russia and the old Soviet block, including both the Trans Siberian (Moscow to Vladivostok) and Trans Manchurian (Moscow to Beijing via Harbin, not Mongolia), so if you have any specific questions, feel free to post them here or send me a PM.
Good luck, and have a great trip
I travelled both Kupe and platzkartny during my trip to Russia last year.
Platzkartny is more Russian. It is the place where fellow Russian travellers offer you vodka and sweets and you make friends really fast (especially when you speak some Russian). However it is also the place where you have to put up with the noise and smell (!) of 20+ people 24/7. It is difficult to wash yourself on the Transsib, so some people don't bother. Socks that are not changed for a week and food with lots of garlic contribute their own aroma. Drunk Russian men also have a tendency to get a bit too friendly towards women, if this a concern.
All in all travelling platzkartny is similar to a stay in a very cramped hostel dorm with far to many people stuffed inside.
Kupe is similar to staying in a budget hotel or a private room in a hostel. Definitely worth it if you value your sleep and privacy.