I see people talking about the hearts online in the discussion, but have never seen them. I wonder if it's an A/B trial thing or something.
Usually when I like things I recommend buying them, but I wouldn't with Duolingo because IMO, you don't really gain anything except no ads. Ads only bother me when I'm trying to maintain a steak and it's getting close to midnight. However, they recently changed it so that even one lesson counts towards your steak, so even if you have your daily goal level set to five lessons, only going one lesson a day will maintain your steak.
Like many things, in the beginning your going to feel like you're learning a ton and you're going to be speaking Spanish in no time! Eventually, the lessons start feeling tedious, which is why things like Extra Spanish on YouTube, watching movies, and looking at other info is important, just to change things up.
Finally, as C.Norris has pointed out, trying to actually talk to people is important. I find that most ladies working at Mexican food places will talk to you (as long as they aren't super slammed or something). Be warned though, as confident as you'll feel going into a conversation, the first time you trip over yourself so hard you'll wonder if you had a stroke. You'll also immediately shift your opinion on people living here and not looking like they are trying very hard to learn English.