Just hit 90 a few days ago, had levelled all the way to 90 as Assassination and it was awesome. Figured Id try combat as I used to like Combat in PvE and Assass in PvP.
Wow, It is AWFUL - trying to take down mobs in the Vale and it takes 3-4x as long as with assass and you lose twice as much health. Even with blade flurry against 2 mobs, my assass could take down both faster.
I'm don't have any problems at all as combat solo. Glyph of deadly momentum and around 15 sec for a mob to die = non stop killing for me, but i am in full heroic gear.
When i was 440 ilvl i don't recall any trouble at all. Do you have leeching poison? It's the best solo talent to pick up. Even without recup up i can finish dailys without going below 80%
Actually, yeah, in quest gear rocking combat can be brutal. I've played combat almost exclusively since vanilla, the last two expacs made combat lazy, you didn't need to do much when solo other than spam SS and Evisc. Now you need to actually use skills to get by, primary is to make sure you aren't doing crap without RVS up, we seemed to be alanced around the assumption we will keep that up at all times, otherwise our CP generation is ridiculously slow, so we can be sitting there forever with 2-3 CP waiting on regen, when with RVS we'd likely be at 5 and could pop a finisher.
TL;DR Combat is quest gear is brutal, get upgrades or use all your skills and correctly.