B2S is a Thai bookstore chain which is operated by Central Retail Corporation, a big retailer in Thailand. The shop does not sell only books, magazines, or newspapers, but also sells stationery, office supplies, CDs, and DVDs. You can find calculators, electronic dictionaries, and e-book readers here.
Even if BTS is a Thai bookstore, you can also find foreign books in this shop. Well, if you are seriously looking for foreign books while you are in Bangkok, I recommend you to go to Kinokuniya bookstore. B2S has rather limited choice of foreign books.
What I like most of this shop is the stationery section. I have to tell you first that this shop sells quality stuffs. Everything in B2S looks nice and pretty. Do not be surprised if you cannot find cheap things in the shop. It is a great place for buying gift for friends.
The shop also has wrapping section, and of course the wrapping papers are so nice! So, it is very convenient, if you want to buy a gift for someone here. And this corner is always crowded during Christmas and New Year period.
If you love the stationery section in B2S, I do recommend you to visit BeTrend. I am sure you will like it too.
Update: December, 2014
Location/ How to get there: B2S has several branches not only in Bangkok, but also around Thailand. You can definitely find B2S in Central shopping mall. I think CentralWorld branch is the biggest one, and it is my favorite one. You can go there BTS sky train (get off at either Siam station or Chidlom station)
Website: http://www.b2s.co.th/ (Currently the website is only in Thai language)
Have you ever been to B2S? Do you like it there? Share your experience with me in the comments!