This book combines the first three Asterix adventures into one volume, thus it is the ideal place to start if you're new to his stories.
The first is Asterix the Gaul which introduces many of the themes that follow in the following 30-odd books: the premise of a Gaulish village resisting against the might of the Roman army; the Romans getting a good biffing from those villagers whenever they attempt to take it; Asterix's craftiness; the magic potion as produced by the druid, Getafix, that gives those who drink it great strength; Obelix who has permanently high levels of strength due to falling into the potion as a boy and he can never have it again as the consequences would be tragic, yet he does want it; Obelix's love of wild boar...
The story is good too. It tells the tale of the Romans sending a spy into the village to find out where their great strength comes from which leads to a kidnap plot on the druid, and Asterix gets involved too, but all ends happily with a great banquet to celebrate (another theme carried through into the other books).
The drawings themselves are a little cruder and less refined than the later books, which is understandable given this is the first.
The second is Asterix and the Golden Sickle. Getafix the druid breaks his golden sickle so Asterix and Obelix need to travel to get it from the only sickle maker Getafix considers worthy. That means a trip to faraway Lutetia (Paris). Trouble is that when they arrive the sickle maker can't be found and the only golden sickles they can buy are on the black market at over-inflated and unaffordable prices. This is all bad news because Getafix needs it urgently for the imminent annual druid conference.
The drawing style is still developing at this stage in the series, and the big village feast image at the end is not there (although the customary feast still takes place) but this is still a classic Asterix tale featuring barbarians, bandits, Romans and much more. What more do you need?
The third Asterix adventure is Asterix and the Goths. It starts with Getafix getting ready to leave the village for the annual druid conference (which is what he was getting ready for in the previous book, although both are still stand-alone). Unfortunately Getafix ends up getting kidnapped by the Goths who need a druid to help them invade the Roman-invaded France. It is down to Asterix and Obelix to rescue him.
A great story with the Goths talking in Gothic text, and lots of humour too what with all the running battles going on and such. The village feast scene returns at the end too. A classic Asterix tale to end this trio of stories. Trouble now is you'll be wanting to read the others.
(This book is listed on Amazon here.)