Great question!
I have the $10 Shannon coin along with the $4 Brock and Tecumseh coins. Here are my first-hand impressions.
All Three Coins The
RCM did a nice job of combining multiple textures on each commemorative reverse. The look of each coin goes beyond that of a "standard" proof coin with mirrored fields and uniformly frosted devices. I think the process the
RCM used to achieve this multi-finish effect gives each coin nice depth and allows for subtle details to be highlighted. In short, I find them attractive.
The heavy frosting that canadian_coins has been so good about chronicling is found on the portraits of these coins as well. However, unless you plan only to look at these coins under magnification I don't believe it is too much of an issue. Yes, the faces of Brock and Tecumseh could be a bit sharper, but they are not so "soft" as to be lacking in key details.
$10 HMS Shannon Very nice detail on the ship (including the sails!) and background harbor elements. The gold cameo of the Shannon's original figurehead is a nice touch, but I wouldn't have missed it if it wasn't there. Overall, I nicely executed design.
$4 Brock / $4 Tecumseh Some have noted that they find the reverse too "busy," no doubt due to the repeating "War of 1812" inscriptions in the background. While I can certainly understand this, I personally don't have any issues with the design technique. I think it gives the coins an interesting look and find it to be a novel way to create contrast between the background and the foreground portraits of each coin - Brock and Tecumseh. I also like the off-center placement and partially front-facing style of the portraits; it's another element that keeps the design of these coins from being "standard" portrait coins.
I'm not a big fan of colourized coins, but the limited use of colour here to highlight Canada's official War of 1812 logo works for me.
Those are my thoughts, hope they've helped a bit. You can probably tell that I like the coins and am looking forward to the 2013 releases of the series!