I have had very few problems OPENING Word, PPS documents with OOo. However, I do have probelms trying to create documents and sending them to MS Office users via email.
Typical response from the file recipient is "can open the file all it shows me some text and jibberish!".
I had better success saving as an XML file and sending, but inserted images don't travel well, if at all.
I like 'free', and use OOo frequently, and Thunderbird for Email. I usually wind up copying/pasting directly into the email, instead of trying to send a file attachment that probably can't be read.
I'm now retired, and 100% MSO compatibility is not a major requirement of mine! If it is, follow the advice of others and spend the bucks for the MSO product you need.
OOo 3.3.0, build 9567, Windows 7 Home Premium, 64 bit.