The fund has done very well in a post-COVID environment due to the runup and acceleration in energy prices but with your question as to whether or not it is a strong long-term investment, I would argue no.
If we look to past historical data of the index it tracks, which is the Alerian MLP Infrastructure Index, it has underperformed the markets by a gigantic margin over pretty much any timeline outside of the last 3 years.
To give you an example in dollar values, $100,000 in this fund 10 years ago is now $135,000, whereas $100,000 in the S&P 500 over that timeframe is $344,000.
If you have this in a taxable account, it becomes even worse as your high levels of distribution cause a lot of tax drag. your overall dollar value would be much lower than $135,000.
I'd view this as more of a short-term play on energy if you wanted to purchase it but this wouldn't be something I would personally look to own in the portfolio over the long term.
I've attached an image to highlight previous returns.
