I've seen a lot of bad fan films based on / inspired by Star Wars. Most are awful; cheap-looking with horrible acting and effects. This one is no different, but it commits the added offense of completely ignoring characterization. The Jedi, Boba Fett, and Darth Vader all have their own personality (yes, the Jedi as a whole have a characterization because, except for a few, they have no personality outside of the singularity of being a Jedi). It's one thing to have your own vision, but it's quite another to decide you're going to completely re-write who the characters are because it gets you from your Point A to your Point B more easily.
The number one rule of adapting someone else's work is allow the characters to stay true to themselves. When people complain about actions being "out of character" that's what they're complaining about. For example, you don't have Indiana Jones suddenly decide he's religious or a wuss. Both would spit in the face of the character as they'd been written. That is the major offense of the fan film: the only-works-alone Fett leading a trooper unit to hunt Jedi, the highly emotional Vader telling Fett to stop being emotional, the stoic-in-the-face-of-death Jedi shown running scared from everything around them. These are all situations and scenes from this fan film written with a complete disregard for the characters and who they are. Whomever did this wanted to show Boba Fett fight Darth Vader; they got to do that which appears was the only thing that matter to them, characterization be damned.
The number one rule of adapting someone else's work is allow the characters to stay true to themselves. When people complain about actions being "out of character" that's what they're complaining about. For example, you don't have Indiana Jones suddenly decide he's religious or a wuss. Both would spit in the face of the character as they'd been written. That is the major offense of the fan film: the only-works-alone Fett leading a trooper unit to hunt Jedi, the highly emotional Vader telling Fett to stop being emotional, the stoic-in-the-face-of-death Jedi shown running scared from everything around them. These are all situations and scenes from this fan film written with a complete disregard for the characters and who they are. Whomever did this wanted to show Boba Fett fight Darth Vader; they got to do that which appears was the only thing that matter to them, characterization be damned.