Last year was better than compared to this year because last year bitcoins value is still high but after the start of 2019 , the price fell dramatically.
We can't say last year was better because we haven't seen the rest of this year we're only 2 months in things could get worse for Bitcoin but i'm hoping that it stays somewhat stable until the end of the year.
It is for long term investments. Nothing much has changed.
No mate bitcoin isnt only for long term investment because it can also be used for short or mid term and most importantly bitcoin's primary use is for paying and buying .
You're not wrong but you'll find more success if you go with long term investments instead of short and mid term investments.
If you ask whether the transaction speed is a problem or not, i think there are other cryptocurrencies that have very fast transaction speed aside from bitcoin.
Altcoins does have better transaction speed but they're not widely accepted like Bitcoin.