I have been starting to learn Tai chi. Arguably the "least martial" of the martial arts... I'm not looking quickly to start beating people up :-).
It is a particular challenge in that there are so many little movements involved; I have never been a dancer, so coordinating hands, feet, legs, and body is something new to me.
While the art may appear langorous, that does not imply it is easy, either in terms of coordination, or, for that matter, use of strength. It is by no means an aerobic activity, but correctly moving slowly requires a pretty hefty degree of effort.
There are definitely places where the movements are counterintuitive; it's kind of neat that over time, I start recognizing a new intuition (which really is practice) that tells me both when I'm doing things right and when I'm doing things wrong.
What is kind of interesting is the impact on ordinary "walking around." The excruciating attention I need to pay to my movements during Tai Chi movements does map onwards. I'm becoming a bit more exacting about my steps when doing things completely unrelated to the martial art...
I am gradually moving towards the point where I will be able to, unattended, perform the Basic 24 Form Yang Form. That has the considerable merit that it is a not-very-long workout that provides some nominal health benefits, some stretching, some nominal exercise of strength, and a not-inconsiderable exercise of physical coordination. I could do way worse than to have this as a 5 minute morning exercise to get the blood flowing. And this has the merit of not requiring any special equipment, neither mats nor apparatus...
The question will be what to do once I can claim to have "mastered" the 24 forms of the "basic Yang form." It probably makes sense to start looking at the Zheng 37 form, which is supposedly a bit more martial. I'm not overly after the Ed Gruberman-esque "beating people up" , but having some means of self-defense seems no bad thing. The "martial" use of Tai Chi does seem to be strongly biased towards defense in its early application; the "offensive" parts would be way far down the road...