For the record, I am not affiliated with the production in any way.
Hidden Frontier is probably the Star Trek fan film with the most episodes produced to date. Over 7 seasons (this is the last) they have produced some 50 or so episodes.
This is no mean feat on almost no budget and everyone volunteering their time and energy.
By their own admission, the earlier seasons do not have as good production qualities as later ones but as they progress the effects, green screen work and acting all improve.
I did find it difficult to "dip into" so started from the beginning and watched all the way through. HF benefits from story arcs just like all the best sci fi and dovetails nicely into the Star Trek universe in which it is set. Characters and "relatives" from the original series have been brought into the stories and add a lot to the feel of the stories, sometimes improving on the characters over the original.
The whole experience includes an excellent web site, blooper reels, a high membership forum which is frequented by many of the actors and production staff and a weekly chat.
If you are looking for high definition, high budget productions, this is probably not for you.
If you are looking for continued adventures in the Star Trek universe with stories that does Star Trek credit and makes you think, this is the one.