Atmosphere was very good, and at the time of release it was a very smooth game. Bioshock 2 might be better to some people. But to a lot it is the "been there done that" attitude.
For example imo DW7 and DW7 XL and DW7 Empires was a lot better then DW6. But since it was already done earlier in the gen they were rated worse.
Same with FFXIII-2 and FFXIII.