Of course it is GPL and you can remove it.
I would like to try the paid version, if it was GPL and I can use it on several projects, but that's not the fact.
I don't mind paying for the sub-plugins, but it is very unclear whether these work with the free version or not.
If you are unexperienced user, you better play with it first, before installing on a live site.
I would give 5 stars, if the extension was coming without the link at the bottom.
Thank you for your review. Let me respond briefly:
- I do not see a single reason, why the signature link should hurt your SEO in any way; most of the websites do have a signature of some kind
- as regards the licensing, it is up to you if you decide for the free version or upgrade to paid; as regards the paid version, I think the conditions are fair enough, but thank you for opinion
- sorry if the situation around plugins is not clear, so let me explain: you can use all of the plugins in the same way both for free and paid version
I would say that it is fair, does what it says, however compared to other extensions lacks many features. I especially miss full control over the URLs (i.e. remove categories and similar). For example, I wanted to have a K2 urls with only the item alias, but avoiding the category was impossible.
To be honest, it is a good extension, but its plugin system and extension options are not sufficient enough.
Its interface is also not very user friendly
Regarding lack of control, You may have miss the "Extensions configuration" dialog box, where you can fully control the urls: remove section, categories, add numerical id, use alias or title,etc?
As for plugins in general, we have take another stance from most other SEF component, in that instead of trying to supply and maintain dozens of plugins ourselves, which is next to impossible, we work with extension makers so that they directly provide sh404sef support. It is so with K2, for instance, and all settings to configure URL for K2 are to be found directly within K2, which makes sense in our opinion as the way K2 urls looks is really K2 stuff.