You can ask parents to check and update information about their children through SLG. It's only customisable in a very crude "I do want the page asking if their address is the same, I don't want the page asking them about their child's allergies" kind of way. You can't alter the individual questions. If a parent makes changes it doesn't just upload straight to your SIMS database - you have to manually approve them first. SIMS will NOT automatically tell you if anyone has sent changes in, so you just have to get into the habit of checking that page every so often just in case.
I believe it is available as a bolt-on if you want to pay extra for it. Our school already had ParentMail, so we didn't bite. The welcome page you get after logging in is common to all users, and you can put a general announcements box on there.
We went with the option for Capita to host it for us. That pretty much locks you down to a number of site themes rather than making the appearance customisable. Most of the available themes are garish and/or have other schools' logos plastered all over them. If you want your own making then you'll have to pay Capita extra (and your theme is not exclusive, so anyone else can use your expensive theme for free). If you go self-hosted this isn't an issue though.
SLG displays info through webparts. I find them a nightmare. You pick them from a list, which just gives names with no explanation as to what they do. The documentation goes into great detail as to how you adjust a webpart's title or remove the border line around it...but still doesn't tell you what it does. So you basically have to pick something that sounds likely and add it in. Did you get a blank box? Well, there are two possible reasons. It could be that there isn't data in the right part of SIMS (good luck finding out what/where it is). Or it could be because there are no test accounts or even examples of what output to expect. So unless you (the admin) happen to also be a parent, you will have to find one who will let you log into their account so you can see what on earth you just did. Even after all that, the webpart designs are really clunky and parents don't find them at all intuitive to use, so you'll end up having to write a guide book just to explain to them how to see their child's attendance.
All changes are live. So you'd better hope that no parent logs in during their lunch break or something while you are trying to figure out what a webpart does. Also, you'd best remember to remove that "grades" webpart you added, otherwise teachers entering grade card info into SIMS marksheets will find that what they write is being published as they type it in (and then the parent rings up asking why they have some grades but not others and why the accompanying message is full of typos).
And finally, the biggie. We decided to release reports through SLG only (save paper etc) and my experience is that everyone hates it. Some of it can be chalked up to technophobia - Capita quite rightly insists on strict password requirements, but that means I pretty much have to right-off the week after reports are released because all I will be doing is answering phone calls and emails asking me to manually reset their passwords. You can set up a "secret question" system that allows them to reset their own password. But you can't force them to use it, so most of them don't. This also applies to students - the initial passwords are auto-generated jumbles of characters and 11 year olds really struggle with them. And no, you can't change passwords en mass.
