The setting of Magus Rex will be familiar to any fan of Jack Vance - the far future, outrageous mages with baroque, decadent lifestyles, etc. The concept could be Vance as well - a young man defying adversity in the name of romance. Lovejoy's take is far more personal than Vance's, however - the language is less elaborate, and the protagonist more likeable. Unfortunately, the sum isn't as successful as Vance's efforts.
I enjoyed Lovejoy's A Vision of Beasts series, also about a decaying far future. Here, his turn is more fanciful - there's no attempt at an explanation for why there is magic, or how it works - and largely an excuse for adventure in exotic times and places. It's a decent adventure, but never moves beyond a solid, almost stolid forward pace. Valorius is an engaging protagonist, but his love interest Zenobia, while bright, is largely a cartoon character who would be played on film by a bright-eyed girl in a bikini and revealing robes. The action is fun, but for a book written in the 1980s, the attitudes are pretty tired.
The resolution of the story hardly even bothers to wave a hand at the issue of magic. We just have to take it as given that the plot could work, and let it go. While Lovejoy wrote some entertaining books, this one is a decent third-string adventure that fills time, but breaks no new ground.