How should undergraduate student respond when the PI of their lab asks them to provide feedback on a research paper? I worked on a research project earlier this year with a group of people. The paper has been written up (not by me) and sent to the team to review it, give feedback and approve it before it is submitted for publication. I am just an undergraduate student and this is my very first experience with this. Most other people on the research team are much older and more experienced than me; so I do not have any critical feedback to give. The paper seems great to me.

Anyways, I am wondering how to state my approval when I email the PI? Replying with “I approve of this paper” seems too entitled for me since I am so inexperienced. So what would be the best way to reply back with my approval?
A reply such as "Thank you for the opportunity to review this; I see no changes that need to be made."  is appropriate.  This confirms that you 


Read the paper and 
Are in agreement with the content and presentation.  


As a participant in the work and especially if you're listed as a co-author, point 2 is important.  However, point 1 lets the organizer know that you've completed your task so that they needn't wait any longer on your feedback.

An additional thought:


  Most other people on the research team are much older and more experienced than me; so I do not have any critical feedback to give.


Don't let age or experience of other team members influence how you perform your review.  

You have every right (really, a responsibility) to raise any issue you identify so that it can be addressed.  Furthermore, I've often found that less-experienced team members tend to make very rigorous reviews of all the details, often catching details that others miss.  Take this as an opportunity to dive into the work and learn the intricacies of it (especially the parts you weren't involved with).  This will allow you to gain understanding of the field and allow you to more effectively perform another type of review: that of the overall nature of the work and the cohesiveness of how it's presented.

Also, as you perform the review, you should bring questions to your team members.  They understand you have little experience (you're an undergraduate, that's expected).  However, displaying interest in the work and gaining knowledge in the field is a good thing.