I used this guide during my recent trip to Edinburgh; although I've been to the city before, I don't know it well and wanted to make sure I didn't miss out on anything particularly interesting. Unfortunately, although this guide fulfils the bare minimum of a guidebook's remit by suggesting places to go, in other respects it is a badly-designed and user-unfriendly little book, especially when compared to something like the Lonely Planet Encounter series, which accomplishes far more in as little space.
The first thing that struck me about this guide is that it uses the page count it does have very wastefully. The 'day by day' gimmick is supposed to help tourists by suggesting how to organise one's day so as to make the best use of one's time - for example, there's a walk along the Royal Mile and up Arthur's Seat, or sections such as 'Edinburgh for art lovers', or 'families', or 'Literary Edinburgh'. However, instead of simply referencing key sights and providing a page number to a fuller description later in the guide, Frommer's choose to give a repetitive mini-description each time, so most of the later part of the guide contains little new material. The index is almost impossible to use for similar reasons; rather than a straightforward index, it's organised under headings such as 'Children, activities for', which you can't really anticipate - so initially, an attraction like 'Dynamic Earth' seems to be missing. Then, when you do manage to find the sight you want, the information given is skimpy and unhelpful. For example, you are told to get the train to North Queensferry to visit Deep Sea World, but not how to get there from the station, and the bus numbers to Edinburgh Botanical Gardens are listed, but you aren't even told which stop to get off at or where the gardens are (other than an arrow pointing unhelpfully off the map). Finally, the hotel index is not up to scratch for budget travellers. If you don't want to splash out on something expensive, you're simply pointed towards the youth hostel.
I did not visit Glasgow, so am unable to fully assess the 'best of Glasgow' section, but I do agree that it seems a bizarre publishing choice to include some scrappy information about Glasgow at the end of what is primarily a guide to Edinburgh. Personally, I think it would have been much better to advertise this as an Edinburgh guide and perhaps suggest an itinerary for a one-day or two-day excursion to Glasgow. It's also annoying when you're trying to use the fold-out map and accidentally open it on the Glasgow side - which happened far too frequently! Rather than wasting space on an incomplete guide to Glasgow, I would have preferred to see more information about the culture and history of Edinburgh, with suggestions for further reading - something which other travel guides usually manage. Here, there's only an extremely short and selective timeline, which does little to illuminate Scotland, especially for the uninformed visitor.
For these reasons, I would not buy a Frommer's guide again, and would suggest you get either the Lonely Planet Encounter mini-guide, city guide, or the full Rough Guide book to help you on your way in exploring this fascinating city - even the cheaper, briefer Berlitz guides are more helpful.
Edit: Just remembered another problem with this guide - the fold-out map has a bit of a problem (especially in a city like Edinburgh) in that it completely fails to note where a road goes under another road, rather than turns off it. For example, it implies that Cowgate is simply a junction with George IV Bridge - actually, it's an underpass. Luckily I knew this already, but it could heavily confuse new visitors to the city!