Well i'll be honest and say I've never played another MMORPGs. I started playing STO because It was FTP online and the grinding to get better stuff isn't so bad.
Pros:
- It's star trek and it's free, and it's pretty full every day of players.
- Playing against and with other players on co-operative stuff can be really fun and rewarding, especially on big space missions
- New ships, designs, and factions (currently you can play as FED, Klingons and Romulans) are pretty sweet and updated fairly regular. Also follows stories through (I think most are considered cannon) from the various series
- Very good customisation of both your ship's exterior and interior as well as your captain, bridge officers and crewmen.
- Joining fleets to get better equipment (at lv. 50 beyond) is simple, but getting the equipment requires a lot of grind.
- Cryptic sometimes give away free stuff and organise free events that give you good equipment/ships depending on how much time you want to invest.
Negatives:
- Ground combat. BORING AS HELL. Every other mission will require it, and you can upgrade your levels on it, but really I'd just concentrate everything on space missions and 'get by' on the ground missions even if you die every now and again.
- Literally no point in trying to anything outside the story missions until Level 50 as equipment/ships/character traits are all useless until you reach the top level (luckily you can level to 50 within a couple of weeks with a decent amount of time invested - Cryptic sometimes do double XP weekends every other month as well. It took me 3 days of intense playing to level my romulan captain to lv 50, although I didn't pay any attention to the story missions and just clicked through the dialogue to finish missions)
- Can be expensive to level up to much more powerful ships - STO beyond level 50 is really fun for PvE (against computer with or without a team) and PvP (against players who have also reached lv.50). PvE doesn't matter so much as long as you've gota decent ship, but in PvP you will need something with considerable firepower to match even medicore players. This involves a LOT of grinding or just paying out for better stuff. But the for the really, really good stuff you need both, which puts a lot of people off, including me to a degree).
- Similar to above, the very best equipment can only be gained through joining a fleet (easy) who has unlocked all the higher level starbase stuff (difficult), which you have to contribute to. Once this has been unlocked, you then need to do some personal grinding to get the items (very difficult). An example:
Fleets have bases (say, a star base or dilithium mine) that go from ranks 1 to 5. Rank 4/5 will unlock the very best fleet variants of ships (typically more powerful than non fleet variants which can either be bought for real money (converts to ZEN through cryptic) or gotten through grinding for in game money which is traded for equivalent credits/ZEN in game on an exchange. The latter can literally take months if you're a casual player, which I am.
Upgrading the base itself can also take months depending on how active the players are. Typically upgrading one level will require a few million of the required in game credits (usually dilithium, energy credits, 'experience points' and so on - No need to go into detail, just realise you need to grind for all 3), which can be quick depending on how many players are in the fleet and how active it is. Not so bad usually because most big fleets have open invites and everyone can share the spoils.
Once it's upgraded you then need to grind to get the ship (my ship cost 2,500 zen, so around £20 or $30? - around 2 months work or so grinding in game dilithium which can then be traded on the exchange for zen, or for energy credits - complicated, again, no need to explain really). Once you've got that, and you want the very best weapons/consoles/duty officers (which add buffs to your ship), you then need to grind AGAIN , which when fully loaded probably cost 6 or 7 times the ship. To be clear, you can't get the best stuff outside of a fleet.
There's a few more pros and cons but those are the best and worst for me. Obviously you expect a level of grinding in any MMORPGs, but a lot of people level some criticism at cryptic with how much potentially there is. That said, Cryptic have allowed players who want it 'now' to simply buy it in most (but not all) cases.
There's also nothing better than flying in a fleet of borg with some friends and letting rip on the closest borg cube and helping/shielding downed friends who are taking a battering. Very fun.
I've also managed to grind/buy my way to a pretty awesome fleet battle cruiser for the Federation which can dish out a lot of punishment:
http://sto.gamepedia.com/Fleet_Avenger_Battle_Cruiser (also gives you a little example of how normal variant ships are inferior to the typically more expensive and more difficult to get fleet variants which require all the grinding). A lot of people on STO don't like the design, but for the style and class of ship it is (a cruiser which are usually big, Enterprise type ships) it's small, fast and compact. The little designs are also cool. Because it;s a through and through warship the windows are all closed during combat and replaced with a hard shell from the hull. I've also modded mine out with various Borg consoles (again, a lot of grinding - around 50+ Days) which have made by ship look like a borg vessel rather than a fed one (similar to this):