Strengths: I used the Medium 2.3 MRC tire as rear tire twice. It has excelent grip I was very impressed. Even a year later, while falling apart (read weaknesses), the grip is still good at any kind of terrain (not too muddy of course), and I think that for about a year they are very good.
Weaknesses: After a year, or year and a half, cracks start to apear in the rubber, and later side knobs start falling of the tire. However, I don't expect any tire to last longer. It is just wierd that it happens, but I must mention again that it happens after quite long usage.
Very good tire, with great grip. I would have given it 5 rating, but decided to go for 4 since some side knobs fell off, but it is understandable after so much usage.