First of all, it's not like every participant gets 25K. Getting that level of funding would take some serious doing. It looks like 1-5K is more likely. Additionally, there are milestones, meetings, course requirements, and a whole lot of work required to get any significant funding. This might not be so bad for many early stage startups, but as a full time MIT student, taking on the extra workload is daunting.
In my opinion, it's not worth it. I am paying ~30K PER SEMESTER to be at this place, so I'm doing my best to focus all of my attention on learning my craft and jumpstarting my career. 25K sounds nice and is definitely nothing to scoff at, but in the broad scale it's a drop in the bucket, and requires getting all tied up in MIT's red tape (and also "Students who receive +$5K in funding will be encouraged to give back to the Fund or MIT"). There are easier ways to go about getting 1 to 25K in strings attached seed funding as an MIT student. The mentorship is potentially a good benefit, but I already receive mentorship from my professors.
I'm sure there are some students who might benefit from this, but I'm not convinced.