I am totally and pleasantly surprised by:
1. the easy of use (I originally selected JoomACE because I had read it was easier to use ... this is absolutely not true!)
2. the easy of installing (removed Joomace and installed sh404SEF and in 3 minutes I had the right settings to have exactly the same urls as I used to have).
3. the excellent information everywhere on the settings and on the website.
4. the forum with all questions answered and clearly answered (for example in Safari I could not manage to change the custom 404 error page and one quick search on the forum teaches in other browsers it should work and indeed ... no problems!)
I did not yet try the extra things like having google analytics integrated or switch to mobile template (will try these in the near future).
I do thoroughly enjoy the inbuilt '404 request manager' which lists all urls that ended up on a 404 error page. With one click you can redirect these to an existing url (through a concept called 'similar url' which is in 95% of my cases correct, making it really extremely easy to get all links working again or redirected to a page of your choice).
After all the difficulty with ACESEF, I am extremely happy to know SEF can be easy as well.
By the way also menu localisation (a Joomfish extension making it possible to hide certain menu items in one language only) works excellent (with ACESEF it does not because ACESEF makes you disable the JFRouter plugin and apparently menu localisation works only with the plugin enabled).
In short: Excellent! Bravo for the developers and the support team.
After a few weeks I had some questions about RSS which I could not get to work, I received replies immediately 3 times in a row. Also the support forum is excellent.
I am very impressed.
It is real easy and works very well. Make sure you set it to 'no cache', at least for me that helped!
I use it so site visitors can keep track of the articles they like best, without having to log in.
The site has also a lot of documentation (especially for members, which is paid for but it is absolutely worth every 'penny').