I think for Hackathons to be a positive experience it depends one two things.
First it has to have an end goal where, even if you don't come in first place, you still leave with something that will be useful. From an incredible learning experience to something that could make you money.
Second it shouldn't cost you anything directly except for time. Working extra hours for your own company? That's costing you more than time because it's becoming a requirement ("Look at Johnny over there, he's gone to all our hackathons and now look at him in a more senior position. Do you not want to move ahead?").
For instance I just finished participating in Launch's Hackathon this weekend. Other than the costs I paid for my travel I paid nothing but time (they provided all food, drinks and not all of it was unhealthy) and in the end, even though I didn't win a prize, I left with the start of a really cool product (if I do say so myself) where, realistically, I think I'm about a week from delivering a decent, beta experience. I even created a Twitter account just so I could post my fun experience as I went: @heysimex
TL;DR: hackathons that cost money, that don't provide you with SOMETHING useful even if you don't win or that are run by your own company are rarely good experiences (unless you win). Hackathons that cost you nothing but time and you have something at the end of the thing? Awesome. I love it!
First it has to have an end goal where, even if you don't come in first place, you still leave with something that will be useful. From an incredible learning experience to something that could make you money.
Second it shouldn't cost you anything directly except for time. Working extra hours for your own company? That's costing you more than time because it's becoming a requirement ("Look at Johnny over there, he's gone to all our hackathons and now look at him in a more senior position. Do you not want to move ahead?").
For instance I just finished participating in Launch's Hackathon this weekend. Other than the costs I paid for my travel I paid nothing but time (they provided all food, drinks and not all of it was unhealthy) and in the end, even though I didn't win a prize, I left with the start of a really cool product (if I do say so myself) where, realistically, I think I'm about a week from delivering a decent, beta experience. I even created a Twitter account just so I could post my fun experience as I went: @heysimex
TL;DR: hackathons that cost money, that don't provide you with SOMETHING useful even if you don't win or that are run by your own company are rarely good experiences (unless you win). Hackathons that cost you nothing but time and you have something at the end of the thing? Awesome. I love it!