The problem I've heard voiced about many F2P MMOs -- feeling built with different areas pushing you to their cash shop -- doesn't quite jive with me. I always thought older cash shops felt tacked on after development. It's as if developers finished the game, then the marketing department looked at how they could sell something to cater to a wide player-base. RoM's many items feel much more woven into the game as an integral part that touches on every level and every other feature. In a way, RoM's shop is comparable to games that do a better job at hiding or dividing a grind amongst fun play mechanics so it doesn't feel like a grind. Like any MMO that does a good job of making grinding fun, RoM does that same thing with their cash shop.
Let's look at the Arcane Transmutor that's used in many different ways. Even if you buy Purified Fusion Stones from the shop, you still have to use them in the AT like everyone else. If a person was impatient or didn't know what they were doing, they could wind up making a weapon that could be bested by someone using the in-game dirty fusion stones. A player who didn't pay real money could also take a while longer and get their hands on some very nice fusion stones that could outdo someone using PFSs. A person still has to raid, play the auction house, or PK trade for the stats they want and do the work of creating mana stones and applying it to an item they want. Even if you're just raising a rune's tier, you have to get the runes through playing RoM.
The AT also consumes energy every time it's used. Charges can be "instantly" purchased to give you more uses, but even then it's to power the AT in a certain manner that the player chooses: to get a weapon, mana stone, or rune they want. I think it's fascinating how they've integrated those cash shop items directly into gameplay for any player regardless of class or level. The only times I've seen Frogster flirt with a more instant power upgrade were when they held their infrequent weeked sales on pre-tiered runes.
Another hugely popular aspect of RoM is the way they've fascilitated the trading of in-game currency with their diamonds that are bought with real money. It's been possible to buy cash shop items using in-game currency in other F2P MMOs, but those games weren't built that way which makes in-game prices for their cash items far out-of-reach. Those other games usually have players selling cash shop items for in-game prices that can take players months to grind for. While that is something you could do in RoM, there are so many different ways to craft, combine, and work the auction house that it puts cash shop items within reach of non-payers while keeping the game fun. Being a solid feature through the auction house, RoM's cash shop items also have taken on a balanced value compared to everything else within the game where other F2Ps will have any and every real cash item costing exuberant prices – regardless of any perceived in-game value.
That leads me to my next point about RoM having everything obtainable within the game. I have to admit that I get frustrated when I hear people vaguely stating a player will end up spending lots of money in endgame. The truth of the matter is that it depends on what you want to do and RoM gives you a lot of choices. There's a fairly clear incentive to start spending money when you reach level 50-plus, but the in-game alternative isn't only hours of grinding that will turn you into an emotionless zombie clicking endlessly on resource nodes. Some guild mates recently told me some really interesting ways to make lots of gold using a combination of fun gameplay. Creating mana stones by farming some different instances and mobs, then using items obtained by turning in Naga tags, and other varieties of gameplay that can get you lots of gold. It's really a fun part of playing not unlike playing the market in EVE Online or World of Warcraft and the rewards are a free way around getting better geared at high-level.
I haven't really touched housing which is a big part of the game. There's quite possibly more legitimacy in someone complaining that you have to buy a couch, or other fluff item that you can only get by first trading gold for diamonds. There's no other way to obtain parts or different stats or any other variety when it comes to obtaining furniture. Regardless, the main point I want to get across is that indeed you can play RoM, experience everything it has to offer and have fun doing it all for free.
I've had competitive spurts, but it's never been central to how I have fun in an MMO. I've never really felt large incentives to spend money to get my gear faster or easier because of a notion that I can't compete. I have realized that some of the slightly complex routes to in-game-only fame and riches have been enough incentive for me to want to spend some money and get strong enough to experience more PvE fun sooner rather than later. The way RoM's cash shop is so finely ingrained into the game can pleasantly cater to my mood and many different ways other players like to have fun. Perhaps the players that will have the most fun are the ones that love to play an MMO's market and find a challenge in hunting down and creating different items that take a bit more know-how and time to earn that extra gold, because they are going to have all that fun with the reward of playing entirely for free.