Bought this S730 a few months back, the sound imaging is superb.
The bass is very good, very punchy and not boomy at all (could be a bad thing, depending on your taste, SPF or SQ).
Very sweet bass for music.
Yah, the mid is definitely a bit lacking, but already much better than my previous Logitech Z680, and bit better than the old but still good Altec Lansing 640.
If you have a good sound card which lets you tune, you could punch up the mid levels a little and it'd help a lot for the mid.
This is a very good set for music and gaming for PC / Console.
The cons is the lacking 5.1 effect from movies.
If movies are your only bread and butter, steer away.
S730, The mama of 2.1