While I do somewhat agree that the game has some neat stuff in it, here are some issues I've had while trying to play.
First, and as was mentioned before, a lot of the quests later on can be very difficult to complete, almost making the effort not really worth while unless you've got butt loads of levels. It's either you'll not be able to locate the item needed to complete it, you'll know where to get the item because someone's been gracious enough to tell you but you get one-shotted by the NPC that has the item or on your way to it, etc. the disappointing thing for me was that the quests in the newbie zone were actually really fun and well done, so I was quite surprised to see that that had changed for the later quests and that I basically wasn't able to complete a lot of the ones suggested to me, unless I had help from a very high-level friend of mine.
The second problem I've had with the game is that there's a lot of the areas that are suggested for ranges of levels, but these ranges are completely inaccurate. when I had an opportunity to ask a friend who'd played up to a much higher level and who also had a builder character and would sometimes work on adjusting areas, he basically told me that the ranges in the areas command couldn't be trusted. Of a similar sort, when you decide to start a predator character, you are told by it's description that they basically have their own gear, which turns out to be true. While the gear that a Pred can use is amazing, there's absolutely no way that you'll ever get that gear on your own, unless you've already morted at least twice. When you look in the areas command and see the Predator planet listed, you'd think that you could get up to around level 30 or 40 and that you'd at least have a chance, but unless you have those few morts already, you'll get a very swift spanking and a nice big chunk of xp, down the tube.
Basically what this all comes down to is that leveling up to about 20 is not super bad. It might get a little slow around 15 or so, it gets hard to find stuff to kill for the xp you need for leveling, but it's okay. When I started having the most problems though was probably about 25, at which it was very difficult to find areas to run that had stuff I could actually kill for xp. It was either that I'd find an area that would give me somewhat decent xp and I'd run 60 percent of it and then get one-shotted and lose over twice as much as I'd made that whole run, or I'd find areas that I could run pretty safely and I'd get no xp for the kills there. This is compounded by the fact that there's no way, that I know of at least, to restart a character if you've messed up their stats and such. I know that you can redo stats once you mort, but getting to 40 so you can do so is no walk in the park. there's also no real documentation that I've found that tells you exactly how the different stats might be used in a build of a character type. While stats seem to be very important to how well you dodge attacks, your hitrol and damroll, how many practices you get when you level, unless that's been finally changed, not having a way to figure out how stats are going to affect your build really sucks the big one.
My third and final complaint with the game is how XP loss works when you get killed, even at lower levels. This isn't only with deaths given to you by an NPC, it's the same with deathtraps, scripted deaths, as the game likes to put it when your mining laser explodes when you're trying to gather resources, bla blah. On a level 15 predator, when I get killed, it happily tells me that I just lost 150000 XP. Citizens in the town for me are about 4000 XP a pop, which I don't figure is all that bad, but that one DT I just hit, that one time I tried to mine resources and the miner exploded, that one time an NPC that doesn't even look like a guard decided to auto-assist and one-shots me, there goes pretty much all the xp I'd gained. I can see where if I had the extra morts and levels to actually be able to kill stuff in the upper levels that things might actually be super fun, but with the current unbalance in combat, XP gains in areas, stuff you can and can't kill, difficulties in a lot of the quests, it's just not all that enjoyable. I will note that once you've managed to lose all the XP you've made from getting killed, even though it tells you that you just lost another 150000 XP, it doesn't actually take levels away. I'll also note that I have two characters here so far, a level 15 pred and a level 38 one, which are both pre-mort, so as for how things might be different after that first mort, I can't say.
Take care.