Is discounted cashflow analysis reliable?

Isaac is completely spot on! That is why equity research analysts can come up with vastly different recommendations- buy/sell/hold. Moreover the publishing of these Equity Reports from large investment firms and banks often have hidden agendas as they/their clients hold these individual stocks in their portfolios and thus have an incentive to promote and convince general market sentiment towards their position.

DCF analysis may also be more inaccurate for smaller cap companies with largely unstable and unpredictable growth rates. A small cap specialist once shared to me that any of his predictions of cashflows 2 years forward based on current trends have largely been completely off. Therefore forecasting terminal CFs can be extremely difficult, and render the calculated instrinsic value of the stock inaccurate.

One of my ex-bosses told me that your "Valuation is your story", and your valuation can spin according to how your story is told.

I think the main challenge with DCF is in the assumptions that you put behind the numbers. Small changes in numbers, such as for discount rates, can cause your final EV to look very different. As such, I think it would be quite tough for someone not thoroughly familair with the industry and the business they are modelling to actually come up with a proper DCF. Comparing the final output to other forms of relative valuation might give a better "sanity check" on the numbers plugged into the DCF.

So I think it would only be reliable if the numbers and assumptions you can make are actually justifiable. If not, wrong assumptions plugged in can cause very different forms of valuation.