Since other reviewers have mentioned it, I should say that the games are not designed to run on Windows 7, though the seller describes them as such. The manual list only Windows 2000, Windows XP, and Windows Vista (unsurprisingly given that they are several years old). I played them on Windows XP.
As to the games themselves, I found them great fun, and a real challenge to someone who enjoys puzzle-oriented adventure games. Aura 1 and 2 are very much like Myst in style, though, as reviewers of the individual games have pointed out, they don't have the same polish. Yes, the plot (that runs through both games: they are, to all intents and purposes, one game) isn't anything to write home about, and the narrative in the cut scenes is rather quaint - though I found it added a nice touch of humour and individuality.
That aside, what it comes down to is a standard point and click adventure, with logical puzzles appearing at regular intervals. Some objects are difficult to find, and some of the puzzles are abstruse; I had to consult a walkthrough on several occasions, but I still enjoyed them immensely. For ten quid the pair I can't fault them.
While I can see while the other reviewers were annoyed at not being able to play on Windows 7, don't let their one-star rating affect your judgement of the gameplay. I recommend that any puzzle-gamer give them a try.