Twenty years ago, buying a complete works of Mozart would have been an arduous and expensive task. Now that you do so for this price, it seems harsh to knock the product. However, Brilliant's collection is not the only option. You can, for example, invest in the much more expensive set assembled by Phillips. So, which should you go for?
By comparison with other recordings that I either own or have heard, some sections of Brilliant's collection are a disappointment. I started with the piano concertos by Derek Han and the Philharmonia Orchestra and was unimpressed. As I happen to also have the Phillips cycle by Alfred Brendel and the Academy of St Martin in the Fields, I was able to make a direct comparison by listening to one after the other. It became became apparent that the sound on the Phillips recording is clearer and that the orchestra's playing is more dynamic. Although Derek Han's piano suffers less by comparison, I will stick to the Brendel. It may be relevant that the Brendel cycle was recorded over a period of 18 years, whereas Han's is all labelled as being 1992. The thought occurred to me that the economics of recording complete works within a short period may not allow the musicians to do themselves full justice.
In addition, a personal reservation is the choice of using period instruments for some of the piano-based chamber music, for example on the piano quartets, two of the five piano trios and some of the solo piano works. Here my problem lies with the sound of the forte piano rather than the playing itself. However others may disagree. On the positive side the difference in approach from most other recordings can be rightly argued to be more authentic and it does make for an interesting contrast.
Despite the disappointments, there are a number of compensations. In particular, the piano sonatas played by Klara Wurtz (on a modern instrument) are excellent. The string quartets are also good, with the the all-important later works being played by the Vienna-based Schubert Quartet.
The symphonies are played by the Mozart Akademie formed by the conductor Jaap Ter Linden in Amsterdam. These, like a number of the chamber works are also played on period instruments. The orchestra has a good reputation, employs musicians drawn from many (mainly European) countries and I thought that the recordings were of decent quality.
In addition to the mixed standard of the recordings, another point to consider is whether or not you really want Mozart's complete works. Almost a third of this collection was composed by the "child genius" before he reached his twenties. In effect, you are listening to someone learning their trade well before they have reached the peak on which their reputation is based. For example the first few operas were composed by a boy in their early teens. The earliest work is a violin sonata allegedly composed by a seven-year old. Although this collection is undeniably good value, you might therefore be better off buying selected works and choosing the best, albeit more expensive, recordings.
Finally, although this collection has been repackaged by Brilliant with improved card sleeves, the are some irritating quality issues. As identified by other reviewers there are some sleeve labelling errors. Another issue is that the box is not quite big enough. The CDs are thus squeezed together in a way that makes finding the CD of your choice more difficult than necessary. My own solution to this issue has been to make space by putting some of those early operas into cold storage.