IDK what this means

Thank you for your freshman application to the University of Michigan College of Literature, Science, and the Arts for Fall 2018. After an initial individualized and comprehensive review of your application, we have determined that we will need additional information in order to make a final decision. We will not re-evaluate your application file until after our regular decision deadline of February 1, 2018. We need this additional information and time to ensure that we give your application the best possible review. We will notify you of a final decision on your application by early April.

The quality of grades earned in academic courses is one of several critical factors taken into consideration in evaluating a student’s competitive admissibility. To give your application a final evaluation, we will need any recent grades that are available before mid-February 2018. If your counselor sent the initial School Report for your application through The Common Application online portal, they will need to complete the 2017-2018 MidYear Report using the same method. If your counselor sent your Current Transcript for your application through the Coalition Application online portal, you will need to request that they send your Mid Year Grades from the Official Documents section of your Coalition Application locker. Otherwise, please ask your high school counselor to have a PDF of your grades sent from the issuing institution to our office via an e-transcript vendor or to transcripts@umich.edu, or they may fax a report of these grades to our office at 734-936-0740.

Ive seen others peoples letters and they did not ask for the grades so Im thinking this waitlist could turn into a yes f I keep my grades up.

It is not waitlist, which is a term specific for something else later on. Your are basically deferred to RD and they want further information to support your application.

well this seems like a positive letter compared to others ive seen ? not sure yet

You were deferred.