It is well-known that the EPS import filter in MS Office is very out-of-date (seemingly was not changed much from mid-1990) and can import only limited subset of EPS files. Official Microsoft website provides little information on it but it tells us that
The Encapsulated PostScript graphics filter (Epsimp32.flt) supports the Adobe Systems Encapsulated PostScript Specification versions 3.0 and earlier.
(refs: 1, 2). The PostScript Specification version 3.0 dates back to 1992 year when it was published by Adobe. From that time it was extended essentially. Note also that PostScript Level 3 came at the end of 1997 and one should not be confused with these things: at the time of PostScript Specification version 3.0 only PostScript Level 2 was was introduced.
Besides that one should keep in mind that MS Office works only in sRGB colorspace and renders graphics in the other colorspaces (such as CMYK so much loved by Adobe) incorrectly. But since in the case of embedded EPS images it sends the original PostScript code directly to a PostScript printer (and only to a PostScript printer, other printers will receive a low-resolution raster preview!) it may be not so bad idea to work with CMYK EPS files in MS Office: despite incorrect on-screen rendering they will print nicely (but only to PostScript printers!).
As to my experience recent versions of CorelDraw and Illustrator produce EPS files compatible with MS Office (although it is necessary to turn off generation of CMYK colors and work exclusively in RGB colorspace).
If you see a placeholder instead of a figure it simply means that the EPS was not imported because the MS Office EPS import filter cannot handle this particular EPS file. One possible workaround is to import this EPS file in Illustrator or CorelDraw and then export it as EPS again. The EPS file produced in this way should be compatible with MS Office EPS import filter. You could try the same method with Inkscape although EPS files generated by Inkscape are not always compatible with MS Office. Another approach is to convert EPS to PDF using Arobat Distiller, then open it in Acrobat and export to EPS, but again EPS files produced by Acrobat are not always compatible with MS Office.
Free utilities pdftops and pdftocairo from Poppler utilities for Windows provide another option. They create MS Office compatible EPS files from PDF when are launched with -level2 -eps option:
pdftops -level2 -eps input.pdf pdftocairo -level2 -eps input.pdf It seems that the only difference between them is that pdftocairo produces compressed EPS file while pdftops not.
Note that if the PDF file contains transparent objects they will be rasterized when converting to EPS because EPS basically does not support transparency. In such cases Acrobat or Illustrator can be used to get proper EPS file without rasterization.
P.S. Here is published an interesting example of EPS file which can be imported in MS Office and is displayed incorrectly but can be printed to PostScript printers correctly.