I have been leveling a new character on Tribble like everyone else. I am going to compile difficulties found leveling in this thread in the hopes that Cryptic take a look at it. I welcome all feedback.
1. Certain boss scaling. This is a big problem for some people. Namely the Undine Dreadnought and the Phantasms. Both are very difficult / borderline impossible to do alone.
2. Dilithium Shortage. I know this will be addressed once Dilithium is rewarded as it is supposed to be so its not really an issue.
3. Captain Ranks. Once you hit captain the episodes stop giving enough skill points to level you up every mission. By the time you are approximatly Captain 5 it is effectively 2 missions to every level. With the episode system the way it is this leaves you with 2 options. Replay missions you have already completed (not very desirable for new players) or take a break from the episodes to do the "Patrol" missions. However at Captain rank these are in Cardassian space. Flying between Cardassian space for patrol missions and Romulan space for episodes is pretty fail and will certainly frustrate new players.
I would suggest lowering the level required for the Romulan missions so that, while you must still play them in order, you need only rank up once per 2 missions.
4. Reward Scaling. The rewards for completing episodes does not seem to be scaling along with the required level to do the episode. The early Romulan missions should not be rewarding Mk V gear. This problem is also present in the later Klingon missions / Dividian missions. Due to the Dilithium shortage I was flying my Sabre Escort during the Commander ranks using only Mk V white gear as there were no better rewards available.
5. Cardassian Missions. Having reached Captain 10 you finally gain access to the Cardassian missions. The first of which awards a mear 500 skill points and a Mk VII kit. Way below what is worthwhile at that rank. This is the earliest level it is possible to accept this mission as the last Romulan mission requires Captain 10.