There are use cases where OpenOffice is a vastly better tool for the task at hand. For instance, reading a CSV file that happens to use extended UTF-8 characters with some fields that have important preceding zeroes. In these situations it is possible to import the data into OpenOffice without the prospect of it being mangled by 'clippy'. Sure you can create a new spreadsheet and import a CSV file from disk into it with the data read as 'just text' in UTF-8 but the people I send CSV files to do not do that with their Microsoft ways. Consequently you get so far in and realise you actually need to re-read the source data because it has been Microsofted with bizarre things like capitalisation.
Excel obfuscates data and obfuscates filenames. It also promotes arcane ways of working, e.g. vlookup things held together with blu-tak and string when a simple table join on the original data does what is required correctly with no hand-crafted nonsense.
Too often I see things being solved in Excel where a small bit of code does a better job of creating the report or things like Fusion Tables do a better job of fancy presentation.
I no longer lock in to Excel world, I don't see it as a professional tool.
Try collecting some accounting records in LibreOffice Calc and then finding your accountant uses Excel. Time lost fixing the mess is probably worth more than the cost of MS Office for a single incident. If you need this kind of interoperability more than very occasionally, that alone could be a deal-breaker.
Also, LibreOffice 5 on Windows 7 appears to be a disaster. We installed it for the first time a few weeks ago, on one new PC at work just to try it out, and it's exhibited numerous very obvious graphical glitches, crashes and performance problems so far even just doing basic spreadsheet work. It also seems to have arbitrarily changed a bunch of things from earlier versions, such as the default colours available for colouring or highlighting cells in Calc. Maybe the stability is better on Linux, but even then the changes from LO4 are presumably still the same and just as frustrating.
Sure. The first example we noticed was that we loaded one of our most important spreadsheets into Calc, and found that most of the colours we use to code different cells don't seem to match the default palette any more. Where we used to just click a couple of times on the toolbar, now it seems we have to manually configure the exact colour or use format painting. Someone in our organisation has to update this particular spreadsheet very often, and that kind of change is going to be horribly frustrating for them (or would be, I suppose, since presumably we're not going to actually migrate any existing systems to LO5 in its current state).
All I can really say is that it was immediately apparent that a lot of the colours we used to use, which came from the default palette in older LO versions, aren't in the default palette any more, and if you go to the corresponding places in the format dialogs those colours do show up as "User" in LO5.
We'd have to look into the sorts of changes you mentioned if we were going to stick with 5, so thanks for the suggestions. However, given the graphical glitches and instability, which unfortunately make it borderline unusable on our test system, I don't think we'll be considering a larger scale migration any further until (I assume) some future updates that fix those things have arrived.
The glitches and instability appear to be across the whole suite, BTW. Basic stuff like drawing menus, toolbars and tabs is broken in very obvious ways, all the time. I'm guessing there's some fundamental problem with the routines LibreOffice uses to draw those graphical assets instead of the standard Windows functionality. Either that or there's some horrible conflict with the graphics drivers on the new machine, which is always a possibility but would be surprising at this point given how many other programs do seem to work OK.