Yes, I have two - a Minolta II and a IIIF. I also have a spectrophotometer, but that needs to be hooked up to my laptop. It's difficult to say how useful colour meters are generally - it all depends on what you do. Having a colour meter is important enough for me that I have the spare. If you have managed without one so far, I suspect that having one wouldn't make a difference - I got one because I wasn't getting the results I wanted.
What do I use one for?
Balancing light sources so that they are exactly how I want them. With neg film it is rarely important to get colour temperature bang on, but it is often important to get it consistent. Even when using only one type of lighting - eg tungsten - there can be sufficient variations in colour temperature to be noticeable. Whether they are acceptable or not is a different matter. If they would be unacceptable, then a colour meter will tell you how to tweak the individual lights with gels. If you are mixing sources then a colour meter becomes even more valuable.
Balancing light sources to a certain selected value, either by gelling the source(s) or putting a filter on the lens. This is more important for reversal colour film than for negative, but it is still sometimes valuable for neg film, especially if there is a big difference between the colour balance of the source and of the film.
Nowadays you can get a USB spectrophotometer for about the same price as a colour meter. Hook that up to a laptop (or whatever) and you have a far more versatile, informative instrument than a colour meter. You may not need that versatility of course (well, not until you try it). A colour meter is handier and most will do flash, which the current spectrophotometers won't.
Standard kit for a cinematographer is a colour meter, a spot meter and an incident meter.
So there it is, in a rushed nutshell. The answer is "It depends".
Best,
Helen