A very weak source of card draw, for the simple reason that it does not do a whole lot unless the runner trashes it. There are a lot of asset comparisons you can make, like Wall to Wall or Rashida Jaheem or Daily Business Show, but I think the most enlightening comparison is to a card that saw relatively little play, to the point that a strictly better version was printed: Anonymous Tip.
Both Calvin and Tip have the same, singular job: to draw a bunch of cards. Let's say that you play Anonymous Tip, you draw 3 cards immediately. You've spent one click, one card, and drawn three cards. If you instead installed and then clicked Calvin, you'd have spent two clicks, one card, and drawn two cards. So, you're already pretty far behind, and you can't pull ahead this turn. In fact, let's say that you install Calvin, and then click Calvin every turn for this turn and the next two. You'll have spent 4 clicks to draw 6 cards - which is the same result you'd have gotten if you'd played Anonymous Tip and then clicked to draw three times. Calvin takes at least 5 clicks and 4 turns to be more efficient than Anonymous Tip.
This is also not including any discussion of how awkward Calvin can be to use. Spending one of your three precious clicks each turn power drawing precludes you from a lot of other activities, such as scoring agendas. Meanwhile, actually drawing 8 cards over 4 turns, in addition to having 4 mandatory draws, means drawing 12 cards and only having 7 clicks to play them all, so in almost all practical scenarios, you'll need far more than 4 turns to make Calvin pay off - the card is not just slow, it is also enormously inflexible.
Before you comment - yes, Calvin has asset synergy that Anonymous Tip does not, synergizes with MirrorMorph, and can draw in patterns that Anonymous Tip cannot. However, these are all relatively small upsides when you realize that Anonymous Tip saw basically no play.
As a runner playing against this card, it is basically never correct to go and trash it. You're spending a precious click and three credits to let the corp draw 2 cards clicklessly - it's like giving them a two-turn advance on actually using Calvin. It's not worth falling massively behind in tempo for a theoretical future where the corp is marginally more efficient every turn.
If you need to power draw and you're not in HB, you're probably better off spending your influence on Spin Doctor and Predictive Planogram, or just using whatever in-faction draw you have. If you're in HB and you absolutely cannot spare the influence, Red Level Clearance, Tranquility Home Grid and maybe even Fully Operational are better options.
Or just play Rashida Jaheem.