Taewez is a great place to stay. I fist stayed in this guest house back in 2002 and when I returned in 2008, I found that although some renovations had been made, the relaxed and cheerful atmosphere remained.
The guest house is located in a residential area, near a market and Temple. Taewez is slightly off of the beaten track and so consequently quieter than guest houses located just up the road in Banglamphu. Despite being located away from the main backpacking drag of Khao San, this guest house is close enough to the main Bangkok sights and within a reasonable tuk-tuk or taxi ride to the main transport links. However, at certain times of the day, because of it's location, Taewez can be a bit noisy.
The guest house has a friendly atmosphere, the restaurant sells a decent menu of Thai and some Western dishes, catering mainly for it's residents. The management are able to offer travellers with advice on how to get around Bangkok, I've always found then to be extremely helpful.
The rooms are reasonable, clean and secure. There is a good range of options available from basic shared accommodation though to private, air-conditioned rooms. For most resident on a budget there is a shared shower facility something that should be familiar to most backpackers in Thailand.
Everytime I go to Bangkok, this is the first guest house I head for. Taewez offers decent accommodation, good value for money and an excellent atmosphere. While staying there, I was able to store my luggage while I took two and three day trips out of the city .