S95 is an excellent compact camera that is small enough to fit into a pocket. It provides good image quality and good performance but it does not have a "large" sensor. Its sensor is an average compact camera sensor which is only about 25 sq mm. Low light performance is OK but it can't be that great since it is a compact with tiny sensor. If you want a larger sensor, get the Leica X1 (APS-C) or Panasonic GF1 (Micro Four Third).
Overall, S95 is one of the best ones if you want a real pocket size compact. LX5 is actually another good competing model -it is larger but has "better" lens.