Strip away all the supplementary material, and judging him exclusively on the movies, I must say Boba Fett is amongst the most overrated characters in Star Wars.
The only thing he has going for him is the undeniably cool looking suit of armour. Apart from that he does absolutely nothing noteworthy, and in TESB they only call him “bounty hunter”, just to show how little Lucas thought about him.
I sincerely don’t understand why he’s so popular with fans as he’s pretty much a nothing character.
You should never look at any specific character in isolation (unless there is only one character in the whole film). The interactions and relations to other characters is also important. Carefully leveraging on the established characters is a great tool that enables to build up a character that cannot afford a lot of screen time. In the case of Boba Fett, it is the interaction with Vader that really establishes the character. Pretty much everyone is scared shitless of Vader in ESB, and yet Boba Fett does not seem to be. Furthermore, it seems that Vader even has some reasonable degree of respect for him. This a perfect example of how to maximise the limited screen time by respectfully leveraging on the established characters.
Of course, this tool can also easily be used in a disrespectful manner to crap on the established characters and ruin them (go to ST for a reference).