While you will not be misunderstood using either case, and I'm certain you will find plenty of examples of both in current language use. I'd suggest this distinction will always remain clear:
Use in when talking about experience meaning a skill level.
I have 10 years experience in Java, as a software engineer.
This tool should only be used by those with experience in astrozoology.
In these cases you are talking about experience as a quantity, and showing that you want to have a quantity of experience within a certain field/subject. You can also change "in" to "with" for the same meaning.
Use of when talking about an experience as an event.
I was underwater for 10 minutes, I thoroughly do not recommend the experience of drowning.
Skydiving is great - the experience of falling at 100mph is glorious.
In these cases you are describing an experience as an event, where "experience" could be replaced with "phenomenon" or "feeling". As such, you are giving more detail on what the exact feeling was by saying "the experience of falling" etc. Here, experience is not quantifiable, it is referring to the general idea of the event.
To use your example of "in the room":
"In the room the women come and go, talking of Michelangelo".
The definite article tells the listener that the speaker has a particular room in mind, not just any room.
In English, the speaker might have said:
In a room the women come and go...
but it would mean "in some room, one which I do not recognize or one whose particular identity is not relevant to what I am saying at this moment..."
In English, we cannot say:
In roomungrammatical the women come and go...
English listeners expect the speaker to indicate whether he or she is talking about a particular room or not.
In the room on the third floor... a particular room on the third floor. The speaker would expect the listener to know which room, perhaps from the speech context or from being generally familiar with the house, or from some other context.
In a room on the third floor... one of several rooms on the third floor, and which one is either not known, or irrelevant, or both unknown and irrelevant:
Your precious painting is in a room on the third floor. Don't worry,
the flood waters will not reach it.
Best Answer
This means that you are able to do something easily. For example, "I find it difficult to do math problems, but it's easy for you."
This is a somewhat uncommon combination. The usage I can think of would be a sarcastic comment that you deem something easy when it really isn't, or it's your opinion that it's easy, similar to "It's easy according to you".
For example: "Everybody else recognizes how much effort I put into my job, but it's easy to you." That is an informal usage, maybe even specific to certain geographic areas.
A somewhat similar usage would be saying "That's easy to you." as a confirming statement or rhetorical question after someone describes something very difficult and then claims it was easy; a meaning similar to, "That's what 'easy' means to you?"
This means that I find something to be easier to do if you do it with me. For example, "I have a hard time doing jigsaw puzzles by myself, but it's easy with you."