There are some informations about price - around 69 CHF. Having lived in Switzerland myself, I can attest that it is not the cheapest country around by a long shot, and still this is a very good price.
There are several considerations when you think about it:
How is it working? It may be a port of the "non-pareil" family of emulators, running the original ROM. In this case, while hobbyist intent may get through, producing longer series of a copyrighted software may get the producer in trouble. In the alternative case (all features having been programmed by them in an operational emulation of the original, as opposed to an emulation of the hardware and running the original ROM), then it is a dangerous road, for the original HP15c ROM was one of the highest points of the computer era, when it comes to accuracy of the algorithms, cleverness of the layout, number of features implemented, ROM size, etc. A daunting peak to climb - in your first attempt.
Screen. While they could have worked with salvaged HP12c screens (all voyager screens could be used for all models - if you look at your 12c at an angle you will see the GRAD indicator - while the 12c does not have trigonometrics) they have developed a dot-matrix screen. While readability seems to be good, it is by no means the same thing as the original.
Keyboard. At this stage, we have just seen renderings and we do not know the materials used and the key feedback. However, we HP-lovers feel that the keyboard is one of the key success factors of the calculators of the golden age - of which 15c is one of the peaks. You cannot know how it will feel until some of us actually test the machine and report.
Speed. It always was one of the problems of the voyager family - even when compared with the slow HP41c (clocked at more than twice the speed). This machine claims speeds 60x ; we know that the new HP12c, working on a similar processor, has been able to do 150x - and from the new 12c (called henceforth 12c+) to a 15c+, you just need to port the ROM and a new keyboard engraving.
If you want to take the risk, you will not go into bankruptcy if you try. This said, there are some other very interesting developments going on - namely the HP41CL from Monte, where you can spend your hard-earned cash. I would get both if I can, but in the end...
... I prefer to wait for the real thing. I will probably get it sooner. Enough said.