You're right, i should have explained better. A majority of people have said things like smoother and better, but the few that have looked more thoroughly have said less RAM/CPU as well. One guy on here said Lion at boot took about 3 GB and Mountain Lion was down to 1.5-2 GB at boot.
I put ML on a 2008 MBP with 2 GB of RAM. After boot, the wired memory is about 300 MB, and total memory in use is less than one GB. SL on the same machine did get along with less than 200 MB wired.
Now, Lion, on my 8 GB machine, usually starts with 700 MB wired, and about 1.3 GB of memory in use.
Now, I'm not sure if this shows that ML is better with memory management, or if OSX is programmed to use more memory if it is available, but it seems like a good sign. Performance on the 2008 machine is still very slow, since Safari quickly uses up the available memory.