Is this internship opportunity worth it? Senior deciding between BB and potentially PE

I was just called in for an interview at a smaller PE firm (the firm is legit, not a chop shop). I was deciding if this fall internship opportunity (meaning fall of this year as in right now) is worth it.

The responsibilities include:

• Perform necessary research and writing in support of the preparation of fundraising
  materials for Real Estate and Hospitality Fund II
  • Analyze market information, property reports, and financial performance of potential
  acquisition opportunities
  • Help track the performance of portfolio investments and participate in related
  management meetings
  • Support client assignments for financial advisory practice

The catch is the internship is for 10 weeks and unpaid except for a small bonus at the end depending on how many hours you work. The description doesn't say anything about having the opportunity to join full-time after the internship is over.

I also have some BB Alternative Investment and Equities Sales/Trading full-time opportunities on the horizon that might be able to work out.

I was thinking if for nothing else, the firm's founders are very well connected and have extremely prestigious experience at the giant PE shops and top groups in the top BBs. Unfortunately, with all this interviewing my grades are bound to take a hit (nothing too major though) but I was thinking this private equity internship could show continued perseverance in the field.

Lastly, how would this experience look for MBA admissions down the road?