I was writing this as a reply to a comment made by @Obsura, but I thought it might do better as a full post.
IFs I've played recently that I have enjoyed
Photopia by Adam Cadre
Author site: http://adamcadre.ac/if.html
Play Online: http://adamcadre.ac/if/photopia.html
Well worth downloading and playing offline just to get the graphics.
This one was a game changer for me. It is a story that can only be told in IF but goes beyond what I'd read before.
Read the PHAQ after you play: http://adamcadre.ac/content/phaq.txt
Lost Pig by GRUNK as told to Admiral Jota
Play Online: http://www.grunk.org/lostpig/
This one is short and fun and hits all the things I like in an IF. I never sat around trying to figure out what I was supposed to do. The puzzles were clever and well thought out.
Violet by Jeremy Freese
IFDB page: http://ifdb.tads.org/viewgame?id=4glrrfh7wrp9zz7b
Play Online: http://iplayif.com/?story=http%3A%2F%2Fwww.ifarchive.org%2Fif-archive%2Fgames%2Fzcode%2FViolet.zblorb
This one is SOOOOOO funny. I love Violet's voice. It took me a bit to get into the swing of the game. It is like a ridiculous movie where things just get stranger and stranger. Not your typical IF.
The Play by Deirdra Kiai
Play Online: http://www.deirdrakiai.com/theplay/
This is more CYOA than IF. It uses the Undum engine. It is a story with surprising depth. Like a CYOA, you make choices as the story progresses. Like an IF, you can pause and look at something with greater detail.
Please note: I have played some recently that I did not enjoy so much. Most of them I was sitting around trying to figure out WTF I was supposed to do. They were like a really bad role-playing session were the GM doesn't let you see your character sheet then opens with: "You are in a blank room, what do you do?" I know nothing of the game world and nothing about my characters motivations. My standard reaction now is "I sit down and knit." And proceed to Live-Action Role-playing by actually pulling out my knitting.
PS: Knitting at actual LARPs is really rather fun. NPCs that were a half my age couldn't understand why I didn't want to run around in the woods in the rain and would rather sit in the "Inn" and knit.