One of the screenshots shows the lock screen which looks to be the same as the one featured on HTC Sense 3.0. The home screens are where most of the changes are made. The icons, including the ones for the phone and for the menu have been revamped.
It is also believed that HTC Sense 3.5 will not require a device with a dual-core processor to run like Sense 3.0 does. There is not too much to be taken from these photos, but check them out and tell us what you think in the comments below.