I use my Bosch GOP for sanding quite often.
Observations: it clogs a lot (but I don't have the dust extraction thing for it). You absolutely have to use a vacuum going close to the tool, otherwise the pad clogs and the clogs scratch. I might try ones of those crepe blocks, as clogging paper is by far the biggest nuisance. I haven't bought the DX add-on as I can't see it working very well (anyone got one and cares to comment?).
You get a range of sanding efficiency at the same time. The corners of the pad move faster than the middle of the sides, but more side-to-side. You can take advantage of this, but sometimes it's a nuisance. An orbital one wouldn't do this.
It's pretty good for keying paint surfaces for refinishing, but I haven't used it for woodwork yet at all. My big Makita orbital is good for that, and I wouldn't try to sand detail with a machine as it's too uncontrollable.
Battery life is poor. I can get about 20 mins of slow speed light sanding. That was with almost new batteries. I think Lithium ion batteries don't have a long service life, as mine are tailing off after about eighteen months, and they don't get punishing use. With three batteries you can get about two hours continuous working, as it takes about 30-40 mins to charge one. Given the inevitable breaks, to get the 'phone, have lunch, etc, that's good enough for all day (the charger catches up with you).
The Bosch GOP battery indicator on the side is rubbish: mine started to peel off, leaving sharp edges; you can only operate it with a thumbnail pushed hard into the side of the tool; it doesn't give the same reading as the drill and impact drivers I have (both types have 3 LEDs but which one is right?).
The Bosch storage system is dreadful: Bulky, silly case with a vacuum formed tray. There's nowhere to put accessories and bits of the case plastic are fragile and break off easily. It wouldn't last a week in a chippie's van. Given you're paying for it if you buy a kit, it must rank as unnecessary added cost. I ended up taking a hot-air paint stripper to bits of mine, to "modify" the storage spaces to fit in things like the impact driver, extra bits, etc. There isn't room for everything and none of the storage works very well. I'll be making a carrying case from wood when I get a Tuit.
It's handy, but if I'd had experience of it beforehand, I'd have got a cheap one from Wickes or B+Q and saved money. If the "blue" range is supposedly for trade use, the green ones must be truly awful now. Bosch cordless tool quality seems to have really gone downhill over recent years. A friend's got the equivalent Makita (white) drill+driver set, and they seem much better made, even if they probably do come from the same Chinese factory. I haven't seen another cordless sander to compare it to though, and being cordless is very helpful for DIY, as you can use it up ladders, etc. much more easily.
A mixed bag. On balance I'm glad I have mine, but I probably wouldn't buy it again.
E.
