Is android lag normal, especially on the nexus 7?

I have had a new nexus 7 2013 for about a full week, and I am very happy with the experience that it has provided me so far. However, I am a first time android owner, and have only had major experience with apple tablets. I have seen many reviews of the first generation nexus 7 slowing down only after a few months. I get it that every device will downgrade in performance over time, but I have already experienced some keyboard lag, and want my tablet to last for at least two years. Should I return my new nexus 7 and wait for the new nexus 10 to come out, which Google has confirmed, get something completely different, or just keep it? Android experienced advice preferred Thanks!