Yes that inyourpocket guide is pretty definitive and has good recommendations.
I think that you'll be surprised at the quality of food/restaurant you will find over there especially in Tallinn. I went a few times between 2001 and 2003 and places I remember enjoying a lot were Elevant (Indian), Pegasus (Upscale/Eclectic), Troika (Russian), Bocca (Italian), O (Upscale/Eclectic). Then there's Alte Hansa if you want to have a medieval themed banquet in a medieval house and there's a local Estonian restaurant called Three Little Pigs which serves hearty local dishes. You should make sure to try some of the local blood sausage.
Bars, clubs and cafes abound in Tallinn, so too in Parnu by the sea.
The local blood sausage is called verevorst and is the traditional Christmas food. I'd definitely try and find somewhere that does pancakes (pankoogid).
It might be worth checking out Pille's blog as she lives in Estonia. She has a review of Stenhus here: http://nami-nami.blogspot.com/2007/08/tallinn-restaurants-fine-dining-at.html . . . I've had a meal there too and thought it was pretty good, especially the strawberry gazpacho.
There's a good snapshot here too: http://thepassionatecook.typepad.com/...
Where to begin? You can get huge stuffed pankoogid (pancakes) at Kompressor, in Tallinn on Rataskaevu street (I think). The “three little pigs” restaurant mentioned is actually Kuldse Notsu Kõrts (The Golden Pig Pub), and they do have wonderful Estonian food there. Maiasmokk is a beautiful, classic café, also in Tallinn.
I highly recommend going to Tartu as well—it’s Estonia’s university town, so lots of nightlife for students (though in August you might find more tourists there than students). Must-see places include Püssirohu Kelder (apparently in the Guiness book as the world’s tallest pub; it’s a huge cellar built into the side of a hill), Maailm (funky restaurant on Rüütli street with famous ice-cream cocktails), and Zavood (a favorite late-night hole-in-the-wall destination).