Só posso citar outra resenha de viajantes de Qype , mas acho que a informação mais importante está lá:
The Thalys lounge is open to 1st class passengers and to Cybelis members as well as to members of the German bahn.comfort program. If you have such a bahn.comfort card, you can bring a collegue, that neither needs a train ticket himself or be a member of any of the programs.
It offers armchairs, a small selection of hot and cold drinks (that you have to buy!), newspapers and magazines, fax and photocopying machines (also charged), a free Wi-Fi connection, Sony computers provided free. There is a charging station for different mobile phones (nice!)
You can rent a meeting room for up to 5 people.
The lounge itself is very hidden on the backside of the main hall of midi station. It is next to tracks 3 & 4 (see photo for a plan) which is convenient if you travel via ICE/THALYS to Cologne/Frankfurt as these trains leave midi on track no. 3. There is a TGV leaving from track 4 - but I do not know where it goes.
I find the lounge nice, but not overwhelming. The chairs are large but unfortunately not too comfortable. Unless handled in other lounges, you have to buy your drinks.
The selection of newspapers is rather small.
Overall, it is nice to have a quiet spot to wait for the trains (instead of any of the meeting rooms or public areas), but it is far from the level that airlines usually offer to their frequent travelers!