Not necessarily. It depends on the tone of voice saying "lecker". When you really emphasize the word it can mean 'delicious', but generally it just means 'tasty' (tasting good but not extraordinary). When you want to say somethings tastes delicious (really really good) a German would say for example: "Der Kuchen schmeckt/ist hervorragend" or "Das Eis schmeckt/ist vorzüglich".
Very good example of how there can be differences indeed. Also about the fact that German and Dutch words would be used in a similar fashion just because they're almost the same in phrasing and writing.
In this context however we're talking about food, hence I do think in this context it does make complete sense.
The only thing I could give as an alternative is 'Strawberries taste nice'. But that would result in 'Erbeerde schmecken lecker'?
German has the verb schmecken which (like English "taste") can mean both "have a taste" (der Kuchen schmeckt gut = the cake tastes good; die Marmelade schmeckt nach Zahnpasta = the jam tastes of toothpaste) and "perceive a taste" (Kannst du das Salz in der Suppe schmecken? = can you taste the salt in the soup?).
- Die Erdbeeren schmecken lecker.
- Die Erdbeeren sind lecker.
- Die Erdbeeren schmecken gut.
are all possible and mean similar things.
And on its own, "taste good" is usually implied: Schmecken (dir) die Erdbeeren? "Do the strawberries taste good (to you)?" (rather than simply "Do the strawberries have a taste at all?").
According to Duden, it's long in standard German: http://www.duden.de/rechtschreibung/Erdbeere (the section "Aussprache" has a line under the "E" marking it as stressed and long; stressed and short would only have a dot). You can also click on the little speaker icon there to listen to a recording.
That said, I pronounce it short :) (And long E in "Erde" or "Erdbeere" sounds a bit odd to me.) So you can find native speakers whose dialect is not quite standard German pronouncing it differently.
You say "eether", I say "eye-ther"....