Some SEO tools promise the world, whereas others focus on a specific aspect of SEO - in this case, rank tracking.

I work for an ecommerce business, so we need to be able to track lots of different keywords for lots of different pages across different categories. This is exactly the kind of use case that SerpWatch is made for. It's really easy to add new keywords (I use SerpStat to find what terms we are currently ranking for, and SerpWatch can make further suggestions based on a seed keyword). Then, add them to your project, and that's it.

You can separate related keywords into separate projects, which are automatically given a fun icon which makes them very easy to distinguish, and the clear, large-font GUI makes it a pleasure to use - which SerpWatch can do because it isn't trying to squeeze links to tons of other tools into the interface).

It's been really easy to see the results of our optimisations with SerpWatch, and the generous rank tracking credits (again, a multi-tool would marmalade credits across multiple tools - here they are all for rank tracking) mean you can use this as your main rank tracker.

I've read some reviews elsewhere where people say "you don't need SerpWatch if you have this tool, or that tool" and at some level that is true. If you only have a handful of keywords to track, and are prepared to put up with a sub-optimal GUI then stick with what you have. However, I'm really glad I have a tool that is designed to track rankings, and do it very well, because everything is there at-a-glance - including a monetary estimate of the value of the changes made. Highly recommended.