Cute romance, pretty typical shoujo manga. The art is very very pretty and I think the mangaka did a decent job of making Lancelot look foreign (the eye shape, his height/build, etc.). A lot of mangakas handle this poorly, often just making the foreigner blond and being done with it.
You won't find much more substance here apart from, as mentioned, regular shoujo fluff. Lancelot's character is earnest and honorable, which is a refreshing change of pace from most male leads in shoujo who are just cookie-cutter bad boy types who are crazy about sex.
I feel like a lot of potential was wasted here. It could have been very interesting to focus more on Lancelot's adjustment to being so far in the future, or his reaction to the notion that he is a household name across the world and is lauded as a fairytale hero. A little nod to ANY part of Lancelot's history--the round table, Guinevere, his conquests--would have been nice, but
a "past love" is mentioned once and then never again.
There's also a mysterious being in the trump card who seems to makes arbitrary decisions on Lancelot's sudden existence in the world, and he changes the rules more than once. No information is given about this character--who it is, what its motivations are, where it comes from.
If you're looking for a cute, short, mostly satisfying read about a classical hero, you will probably love this. However, if you're looking for a story that at all discusses the details of Lancelot suddenly a) becoming real and b) being a couple thousand years in the future, you'll be sorely disappointed.
Overall I enjoyed it for what it was and tried not to think of all the squandered opportunities for plot development and intrigue.