I'm not a heavy user, but I use Outlook as my main mail app, Excel for simple spreadsheets and invoices, and Word for simple info and tech sheets (sales). Excel works perfectly although its a bit like having a giant truck to carry groceries; its way more powerful than I need. Word seems to work flawlessly, I haven't really had to use Word since college before this, and it works at least as well as I remember, probably better. Outlook is sort of a disappointment for me. I would love to sync calendars and reminders with all devices easily through the app(s), but I haven't figured that out yet. I also have an issue with Outlook sometimes not wanting to stay connected to my exchange server, but that isn't necessarily the fault of the program.
People who use more of the power thats offered in these apps are probably better suited to go into detail, but Office meets or exceeds my expectations/need as a light user. If i could get Excel to do a little more, its 10/10.