Yes! 64-bit applications get to take advantage of all the memory in your system. You can now do longer RAM previews, have better caching, and can work with larger file sizes like 2K, 4K or even larger images. Anyone who has ever run into memory limits with large 3D comps will find a big benefit to working natively in 64-bit.
We have found that our own tools are also benefiting from 64-bit. We ran a quick test on Peder Norrby’s Trapcode Particular v2 – Massive benchmark project (you can find it here) which uses most of the Trapcode plug-ins including Form, Lux, Particular and Horizon and the speed improved by about 34%. The total render time dropped by 11 minutes on the same project compared to CS4. Multiply that out by many renders or RAM previews in a day, and that adds up to significant time savings when you use a 64-bit optimized app and plug-ins.