The pace of Blender's development seems to be speeding up. There are some big improvements packed into this latest version! Here's everything new you will find in Blender 2.9.
New Modeling Features in Blender 2.9
Extrude Manifold is a new tool for extruding faces inwards while deleting overlapping faces and dissolving overlapping vertices. You can’t use it to punch holes straight through objects yet, but its initial implementation is already very useful.
Vertex Slide now supports snapping!!!
(I’m adding extra exclamation points because this simple change will save me quite a lot of time when modeling.)
The Bevel Modifier’s custom profile curve can now be controlled with Bezier handles. It also has a new Width Type called Absolute, which lets you specify the exact distance along the edges of the bevel. That often results in bevels of uneven width when two connected edges are at different angles, but it may be helpful in some circumstances when Offset or Width doesn’t cut it.
A new 3D View Transform option, called Correct Face Attributes, allows the transform tools to edit the UV’s and vertex colors of your mesh while you manipulate the model.
You wouldn’t want this checked if you’ve carefully laid out a custom UV map for a hand-painted or baked texture, but this is perfect for objects using tiled textures!
The UV Editor also got a slew of new commands which we’ve had in the 3D View for a long time - Edge Ring Select (CTRL+ALT+LMB), Select Shortest Path (CTRL+LMB), and Rip (V).
Curve editing has a few changes as well. If you reset your settings, viewing the normals is disabled by default in the Overlays popover. This is great for getting rid of clutter in the viewport but makes it less obvious which direction the curve is going. There is also an option to display only the handles for selected points, similar to Illustrator and other vector software.