I highly recommend iWork, and use Numbers and Pages daily. I like the idea of keep my apps all in the Apple family. They work perfectly, and the idea of loading MS Office seems like a step backwards, if not a desecration of your beautiful new MacBook Pro. (Congratulations, by the way!)
Okay, "desecration" might be a bit strong...but why buy a Chevy Cavalier when you could have a Mini Cooper?
It depends on what you need MS Office for. If you will be editing lots of MS Office docs then you may want to install it (it is not expensive). I have Pages and Numbers also (they are cheaper) and they export to Word docs and Excel and I have not had any issues with that. If you want easy to use software and will not be trading files with Office users, stick with Apple. If you are doing lite trading of files with Office users iWorks is probably fine then too. Complex documents may not be totally translated correctly, however.
MS OfficeMac - $$
If you need to keep your Office skills up to remain employable and/or exchanging some files with Windows Office users.
99% of the business world uses Office on Windows PC's. Copy protected.
If you are constantly exchanging files with Windows users, it's better to use Windows because of formatting and slight differences between the Win Office and OfficeMac versions, fonts etc. You can then choose to install Windows onto your Mac in a virtual machine program, then run Win Office in that, BootCamp or just get a Windows PC and Office.
If you plan to remain totally in the limited 6% Mac market share environment with little file exchange options with Windows/Linux users. Copy protected.
LibreOffice - free
A donationware suite of office programs like Office that accepts Office files, cross platform (Linux, OS X and Windows) that offers maximum compatibility, only fonts and formatting could be thrown off a little between platforms. Not copy protected, open source software.
If you wish to be able to open and access dam near anything from Windows users without paying for OfficeMac, don't need 100% or near 100% compatibility with Windows Office, then this is a excellent choice.
If you ever should need to send a LibreOffice file to someone else to edit or alter, you can also send the appropriate OS copy of the installer package and it will cost them nothing to use.