Litecoin was one of the first altcoins to appear so it was heavily inspired by the ideas behind Bitcoin. In fact, it is made to be the currency that will address the major drawbacks of Bitcoin. It is 4x faster (2.5 vs 10 minutes for releasing a block) and mining is somewhat easier.
It certainly has been over the years, even though there were short term fluctuations that are inevitable for any currency. But at the end of the day, it has always been in the top 5 cryptocurrencies.
It is traded on almost all reputable exchanges, so its very easy to get a hold of it. However with the current price at $151 only did you think it has a high probability of increasing in price drastically possibly competing with bitcoin in the future as a means of storing value??
Litecoin is a useful coin and it should give you profits in the future so I do not see a problem if you invest in it, but you should not have any hopes that litecoin replaces bitcoin, litecoin is almost a clone of bitcoin why do you think that a coin that is so similar to bitcoin is going to replace it? If bitcoin is going to be replaced it has to be by a coin that is many times better than it and right now there is not a coin like that.