I've found L. E. Modesitt to be inconsistent between series, and relentlessly consistent within series. Said, another way, I like some of his series (Recluce) all the way, and don't care much for others. Happily, the Imager Portfolio looks to be one of the good ones, and I now wish I'd bought all the books back when they were on sale.
The world of Terahnar is a bit of a departure for Modesitt. It has a determinedly Terran jumble of aspects, built largely on Romance-language cognates and names (e.g., a weekend day of 'Samedi'). Given Modesitt's usual rigor, I assume that somewhere down the road, these will coalesce into some kind of logic - perhaps an Amberian source world or similar. If not, I'm at a loss to understand it. In any case, the names do make it easy to follow the story - the country of Ferrium, for example, is an industrial, iron-based culture.
Character-wise, Modesitt produces his usual - a contemplative, capable protagonist who works hard and always does the logical thing, especially if that involves working hard (and being surprised that others think it's unusual). Rhennthyl is strong, smart, attractive and humble. He suffers the world's injustices without complaint, and overcomes them through sheer indomitability and determination. It's a recipe that works remarkably well. While the emotional arc of the story is fairly predictable, and the character seems very, very familiar, he's still interesting to follow.
Rhennthyl is, of course, a man of many talents, one of which is magic, or 'imaging'. Modesitt likes his magic systems, but he focuses on character studies, not a Brandon Sanderson application of detail. So, imaging is a bit vague, and our hero, logical as he is, doesn't explore it very deeply. Instead, he explores its consequences in society and in personal interaction. Mostly, that works, but I did find myself wishing that Modesitt had applied a little more rigor. Even if we accept imaging's fuzzy outline, Rhennthyl (as with other Modesitt heroes), has a fair number of 'feelings' (e.g., that someone is watching him) that don't seem to fit the magic system at all. That became a little wearing, in part because it blurred the boundaries between worlds - building the feeling that all Modesitt's worlds have similarities.
One such similarity is the traditional strong man, oppressed woman world. I've noted many times before how tiresome I find this, unless you're using it to make a point. In this first book, Modesitt could have told his core story just as easily in a world of equality, and I wish he had.
I'm not much of a food and clothing guy, but if you are, there's some talk of it here. Modesitt doesn't go overboard, and it's easy to skip, but there's seldom an outfit he doesn't describe in general terms and colors, especially regarding women. Dinner dishes are similarly named, but then set aside. Philosophy is regularly dipped into, though in a shallow enough way that if it's not your thing (and it's usually not mine), you can ignore it and let Rhennthyl worry about it until it comes up again. Morals the same, and if you're familiar with Modesitt, you'll be unsurprised that everything comes in shades of gray.
This first book is somewhat dissatisfying in that it is so clearly the first book in a series. It doesn't end so much as stop - not really in a cliffhanger, but it's clear we've only gotten the first part of a much longer story. The good news is that this introduction is enticing enough to go get the rest.
All in all, a strong fantasy with a very familiar tone, and recommended for fans of Recluce.