(No spoilers in review)I cannot say this is the best series of the West Wing. The first series is the best, but this sure is close. I've seen series 1, 2, 3 and 4 - All are unbelievably great. This is better than series 3, it seems more focused and has some great story ideas. All the characters are up to their usual great standards and with some new ones added.
The climax to the series, however, is possibly the best piece of television I have ever seen. Any fan of the West Wing will recognise "2 Cathedrals" from series 2 as a legendary episode - the final episode of series 4 "25", surpasses that.
Right from episode one this series delivers the goods and it carries on all the way through. One or two episodes can't be considered brilliant, but there are certainly no bad episodes. Special mention goes to the episodes "Game On", "Evidence of things not seen", "Commencement", "25", "Inauguration part 1&2" (2 especially) and "The California 47th" - But as earlier stated, there are no bad episdoes.
I cannot wait until series 5 comes out. Once you watch series 4 you will be thinking that exact same thing as well!