This is entirely dependent on how you usually use your computer, and its specifications. From Windows docs:
Configures the internal cache levels of NTFS paged-pool memory and
NTFS nonpaged-pool memory. Set to 1 or 2. When set to 1 (the default),
NTFS uses the default amount of paged-pool memory. When set to 2, NTFS
increases the size of its lookaside lists and memory thresholds. (A
lookaside list is a pool of fixed-size memory buffers that the kernel
and device drivers create as private memory caches for file system
operations, such as reading a file.)
so basically it increases the amount of paging your file system can use out of the total shared pool. This of course, means less for other processes. The documentation is even explicit about it:
Increasing the physical memory doesn't always increase the amount of
paged pool memory available to NTFS. Setting memoryusage to 2 raises
the limit of paged pool memory. This might improve performance if your
system is opening and closing many files in the same file set and is
not already using large amounts of system memory for other apps or for
cache memory. If your computer is already using large amounts of
system memory for other apps or for cache memory, increasing the limit
of NTFS paged and non-paged pool memory reduces the available pool
memory for other processes. This might reduce overall system
performance. This parameter updates the
HKLM\SYSTEM\CurrentControlSet\Control\FileSystem\NtfsMemoryUsage
registry key.
So basically if your ram usage is not to high, it might be worth it, especially when loading and re-loading resources from your hard-drive. Gaming is a notable area of benefit, where often the GPU is doing most of the work, leaving the RAM somewhat free, and the same stuff needs to be loaded constantly. Of course, there is also a GPU cache for that, so the benefit increase is not straightforward.
Bottom line - this gives the file system more page space out of a total shared pool of fixed size, so is not "free".