I'm in two minds about Serpwatch for these reasons:

1) It's screaming out for local search.
2) 1500 keywords and insisting they're tracked at least daily is a little odd. I've worked on SEO projects for many years and all that would do is put me on edge. I'd prefer every 3 days or weekly.

It would open up the market to SMB, SME and microbusinesses who won't usually have someone taking notice every single day. It doesn't work for agencies too well either, as the numbers are quite low. As per the feedback in the questions section, allowing more keywords with less frequency as an option would make more sense for both businesses and agencies and give you one hell of a source for case studies, testimonials etc.

3) how can you track keywords if you can't properly research them? I imagine this will result in more of the 'oh look, a big shiny keyword that I'll try to rank for,' and take all the conscious thought out of SEO.

Almost every other tracking tool includes a keyword research facility so you can assess the difficulty and likelihood before targeting a search term. I'm currently using SERanking to do the research and having to copy and paste or export and upload a CSV to SerpWatch. It's a little bit annoying to have to do that, upsets the workflow and all.

4) It would be great if projects could have folders and/or subfolders, you might have that already but I can't find it if you do? I'd often group them by campaigns, keyword groups or service/product groups (if a customer launches a new range of products, the launch would usually be a folder within a wider project.)

5) Cannibalisation. It's a good idea to know if multiple pages are ranking for the same term so I can de-optimise one of them.

What's good...
1. Tracking against the algorithm updates - it's a pretty cool feature to see how much your rankings tank.
2. Estimated revenue from rankings - though I'd like to be able to edit the number because how could anyone know my pricing structures?
3. Rankings appear to be accurate and include useful information including difficulty (which makes a little more annoying that I have to use SERanking (or other tools) alongside SerpWatch as you can clearly access the data.)
4. The platform is solid, not encountered any glitches.

4 tacos this time, with a decent keyword research facility and more flexibility around how users utilise the cap and I'd probably give it 5 tacos. Weekly checks would mean 10,500 search terms for the same amount of checks as 1500 tracked on a daily basis.