The controls are intuitive and there is a pre-selection highlight to help you never miss a cut. The interaction was designed for artists, by artists, to be as fast as possible. 

• Left Click: Mark edge as seam
• Double Click: Mark loop as seam, stopping at other seams (!!)
• Shift + Double Click: Mark entire loop as seam
• Ctrl + Click: Mark shortest path as seam
• Click + Drag: Draw seam path
• Hold Alt using any of the actions above to clear seams

When Auto Unwrap is enabled, only the UVs affected by the new seam will be unwrapped. This may seem like a small deal at first but, unlike using Blender's Live Unwrap, you will never lose work by accidentally resetting UV's you've previously straightened or projected.

UV Flow's Cut UV tool also works perfectly with Edit Mode symmetry, which Blender's Mark Seam does not!

No seams? No worries
When you unwrap with UV Flow, you can allow edges to act as if they were seams based on their angle, bevel, crease, sharp, or freestyle attributes. In some cases, especially for hard surfaces, you can unwrap a whole mesh without placing any seams at all! Or you can create seams based on those attributes to use as a quick starting point for a manual unwrap. 

UV Flow comes with a context aware straightening command that can instantly straighten whatever you select. You won't even have to open the UV Editor (though it works there too if you need it). You can use it to:

Align islands to the selected edges
Straighten connected edges into a line
Fit quads to a perfect grid
Align the bounding box of complex shapes that have triangles and n-gons to the grid
The rest of the island will be automatically unwrapped around the straightened selection, so you don't have to do any pinning or extra steps. 

Work in layers
Did you know that having multiple UV maps can be incredibly helpful, especially for placing decals? In Blender you can only have one set of seams per object, which makes working with multiple maps quite cumbersome. UV Flow, however, allows you to work with seam layers. It automatically stores seam information per UV map so you can work with as many unwraps as you need without any extra clicks. 

See it in style
UV Flow has its own overlay system that you can customize. You can set seams to be any color, as well as make them thicc and glowy for extra clarity (or just for fun).

UV checker textures can be enabled by default, so that one is always applied to the mesh you're unwrapping without you having to think about it. Even better, the texture is only applied to the selected mesh and the rest of the objects stay in solid view. Every effect is fully cleaned up as soon as you exit the tool.