85mm f1.4 is a very classical lens on 35mm. I bought my first one somewhat 1984 - a Zeiss Planar for the Contax mount - I still do own this lens.
But this lens type is tricky to use: the DOF is pretty shallow as everybody remarks. This has it ups and downs in using it.
I do own the Sigma 85mm f1.4. It is a sharp lens stopped down to somewhat f2.8 and wide open the shots are useable but not really great. And it suffers from CA (and color fringing - even @f8 on the borders(!)). But the main downside is focusing accuracy. This is painful and you destroy a lot of shots...
The EF 100mm f2.8 L IS USM is a much better choice when it comes to image quality and focusing accuracy. But it does not offer the same DOF -of course. But it adds Macro to the portfolio. It is a very great lens - I love it and does really great portrait as well.
Due to my disappointments of the Sigma I bought the real successor to my old Planar f1.4 85mm: The Milvus 85mm f1.4. And the experience was really great -overall.
The downside of the Milvus:
[list type=decimal]
[*]weight (and size): a 1.2 kg lens is really hefty
[*]manual focus (But honestly: more a problem of the canon bodies: the lens has a 270º focusing throw which works really great)
[*]price (even much cheaper it´s still expensive)
[/list]
For more informations: here I published some photos about my Milvus experience as well as the comparison to the Sigma:
http://bit.ly/1U2oCnp
...and I still want to give the Canon 85mm f1.2 a try...
For your point: give the Canon 85mm f1.8 a try: it is really good and reasonable in pricing....