It is always recommended to apply a finish coat. Primer is primer. If you are happy, let it be.

Thanks for replying, christophern. I'm somewhat happy...the Kilz is thus far doing a decent job of freshening up the space and making the hairline crack from moving the home less obvious (not worth it to repair it at this time).

I know primer isn't paint...but I thought of it as kind of 'white-washing' the ceiling, and my co-workers have done it. Yes, topcoating with paint is better long-term for durability, coverage, etc...but I was hoping someone here could better articulate if there are any major issues with just leaving it as primer...I don't want the work of painting if I don't have to, but I also don't want my work in priming to be wasted, ya know?

I did a little more online research and it looks like I'll have better hide of the crappy ceiling with using ceiling paint, so I'm leaning that way...however, when painting I also noticed a few places that are trying to crack, and adding another layer with paint will add weight to those weak areas. Hmm. Either way, gotta get this project done today & cleaned up while my husband is at work.

If anyone else is wondering about this, I found these links helpful:

http://www.contractortalk.com/f8/ceiling-paint-17931/

http://www.homegardenguides.com/garden-forum/home-repairs-forum/92061-can-i-just-use-primer-no-paint.html

Here is a link that might be useful: 2-coats-primer-ceiling-rather-than-paint

I know it's too late now Jessica....but...

Get some actual Ceiling-paint up there!

Primers will obviously "look nice", since there's a new coat of "something white".
BUT....no primer has the hiding-power of actual paint. They're not designed to!
When you can, get out your ACE-Royal Ceiling-paint, SKU#16513, and get a real coat of paint up there.

Guaranteed you'll be glad you did!

Faron

Thanks, Faron! Turns out I don't have my usual shared day off with my darling mess-averse husband, so I'll be painting the ceiling Wednesday. Now I just have to decide if I'll use the Ace ceiling paint (affordable & I know I'm happy with it)...or splurge and try the Ben Moore Waterborne Ceiling Paint (overkill for my project, but always fun to try new products...that's what employee discounts are for, right?)